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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="ACTIONS-FILE"
>8. Actions Files</A
></H1
><P
> The actions files are used to define what <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>actions</I
></SPAN
>
 <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> takes for which URLs, and thus determines
 how ad images, cookies and various other aspects of HTTP content and
 transactions are handled, and on which sites (or even parts thereof). 
 There are a number of such actions, with a wide range of functionality.
 Each action does something a little different.
 These actions give us a veritable arsenal of tools with which to exert 
 our control, preferences and independence. Actions can be combined so that 
 their effects are aggregated when applied against a given set of URLs.</P
><P
> There 
 are three action files included with <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> with
 differing purposes:</P
><P
> <P
></P
><UL
><LI
><P
>    <TT
CLASS="FILENAME"
>match-all.action</TT
> - is used to define which
    <SPAN
CLASS="QUOTE"
>"actions"</SPAN
> relating to banner-blocking, images, pop-ups,
    content modification, cookie handling etc should be applied by default.
    It should be the first actions file loaded
   </P
></LI
><LI
><P
>    <TT
CLASS="FILENAME"
>default.action</TT
> - defines many exceptions (both
    positive and negative) from the default set of actions that's configured
    in <TT
CLASS="FILENAME"
>match-all.action</TT
>. It is a set of rules that should
    work reasonably well as-is for most users. This file is only supposed to
    be edited by the developers. It should be the second actions file loaded.
   </P
></LI
><LI
><P
>    <TT
CLASS="FILENAME"
>user.action</TT
> - is intended to be for local site 
    preferences and exceptions. As an example, if your ISP or your bank
    has specific requirements, and need special handling, this kind of 
    thing should go here. This file will not be upgraded.
   </P
></LI
><LI
><P
>    <SPAN
CLASS="GUIBUTTON"
>Edit</SPAN
>  <SPAN
CLASS="GUIBUTTON"
>Set to Cautious</SPAN
> <SPAN
CLASS="GUIBUTTON"
>Set to Medium</SPAN
>  <SPAN
CLASS="GUIBUTTON"
>Set to Advanced</SPAN
>
   </P
><P
>    These have increasing levels of aggressiveness <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>and have no
    influence on your browsing unless you select them explicitly in the
    editor</I
></SPAN
>. A default installation should be pre-set to 
    <TT
CLASS="LITERAL"
>Cautious</TT
>. New users should try this for a while before
    adjusting the settings to more aggressive levels. The more aggressive 
    the settings, then the more likelihood there is of problems such as sites 
    not working as they should.
   </P
><P
>    The <SPAN
CLASS="GUIBUTTON"
>Edit</SPAN
> button allows you to turn each 
    action on/off individually for fine-tuning. The <SPAN
CLASS="GUIBUTTON"
>Cautious</SPAN
>
    button changes the actions list to low/safe settings which will activate 
    ad blocking and a minimal set of <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>'s features, and subsequently
    there will be less of a chance for accidental problems. The
    <SPAN
CLASS="GUIBUTTON"
>Medium</SPAN
> button sets the list to a medium level of
    other features and a low level set of privacy features. The
    <SPAN
CLASS="GUIBUTTON"
>Advanced</SPAN
> button sets the list to a high level of
    ad blocking and medium level of privacy. See the chart below. The latter
    three buttons over-ride any changes via with the
    <SPAN
CLASS="GUIBUTTON"
>Edit</SPAN
> button. More fine-tuning can be done in the
    lower sections of this internal page.
   </P
><P
>    While the actions file editor allows to enable these settings in all
    actions files, they are only supposed to be enabled in the first one
    to make sure you don't unintentionally overrule earlier rules.
   </P
><P
>    The default profiles, and their associated actions, as pre-defined in
    <TT
CLASS="FILENAME"
>default.action</TT
> are:
   </P
><P
>    <DIV
CLASS="TABLE"
><A
NAME="AEN2343"
></A
><P
><B
>Table 1. Default Configurations</B
></P
><TABLE
BORDER="1"
FRAME="border"
RULES="all"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><COL
WIDTH="1*"
TITLE="C3"><COL
WIDTH="1*"
TITLE="C4"><THEAD
><TR
><TH
>Feature</TH
><TH
>Cautious</TH
><TH
>Medium</TH
><TH
>Advanced</TH
></TR
></THEAD
><TBODY
><TR
><TD
>Ad-blocking Aggressiveness</TD
><TD
>medium</TD
><TD
>high</TD
><TD
>high</TD
></TR
><TR
><TD
>Ad-filtering by size</TD
><TD
>no</TD
><TD
>yes</TD
><TD
>yes</TD
></TR
><TR
><TD
>Ad-filtering by link</TD
><TD
>no</TD
><TD
>no</TD
><TD
>yes</TD
></TR
><TR
><TD
>Pop-up killing</TD
><TD
>blocks only</TD
><TD
>blocks only</TD
><TD
>blocks only</TD
></TR
><TR
><TD
>Privacy Features</TD
><TD
>low</TD
><TD
>medium</TD
><TD
>medium/high</TD
></TR
><TR
><TD
>Cookie handling</TD
><TD
>none</TD
><TD
>session-only</TD
><TD
>kill</TD
></TR
><TR
><TD
>Referer forging</TD
><TD
>no</TD
><TD
>yes</TD
><TD
>yes</TD
></TR
><TR
><TD
>GIF de-animation</TD
><TD
>no</TD
><TD
>yes</TD
><TD
>yes</TD
></TR
><TR
><TD
>Fast redirects</TD
><TD
>no</TD
><TD
>no</TD
><TD
>yes</TD
></TR
><TR
><TD
>HTML taming</TD
><TD
>no</TD
><TD
>no</TD
><TD
>yes</TD
></TR
><TR
><TD
>JavaScript taming</TD
><TD
>no</TD
><TD
>no</TD
><TD
>yes</TD
></TR
><TR
><TD
>Web-bug killing</TD
><TD
>no</TD
><TD
>yes</TD
><TD
>yes</TD
></TR
><TR
><TD
>Image tag reordering</TD
><TD
>no</TD
><TD
>yes</TD
><TD
>yes</TD
></TR
></TBODY
></TABLE
></DIV
>
    </P
></LI
></UL
></P
><P
> The list of actions files to be used are defined in the main configuration 
 file, and are processed in the order they are defined (e.g.
 <TT
CLASS="FILENAME"
>default.action</TT
> is typically processed before
 <TT
CLASS="FILENAME"
>user.action</TT
>). The content of these can all be viewed and
 edited from <A
HREF="http://config.privoxy.org/show-status"
TARGET="_top"
>http://config.privoxy.org/show-status</A
>.
 The over-riding principle when applying actions, is that the last action that
 matches a given URL wins. The broadest, most general rules go first
 (defined in <TT
CLASS="FILENAME"
>default.action</TT
>),
 followed by any exceptions (typically also in
 <TT
CLASS="FILENAME"
>default.action</TT
>), which are then followed lastly by any
 local preferences (typically in <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>user</I
></SPAN
><TT
CLASS="FILENAME"
>.action</TT
>). 
 Generally, <TT
CLASS="FILENAME"
>user.action</TT
> has the last word.
 </P
><P
> An actions file typically has multiple sections. If you want to use
 <SPAN
CLASS="QUOTE"
>"aliases"</SPAN
> in an actions file, you have to place the (optional)
 <A
HREF="actions-file.html#ALIASES"
>alias section</A
> at the top of that file.
 Then comes the default set of rules which will apply universally to all
 sites and pages (be <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>very careful</I
></SPAN
> with using such a
 universal set in <TT
CLASS="FILENAME"
>user.action</TT
> or any other actions file after 
 <TT
CLASS="FILENAME"
>default.action</TT
>, because it will override the result
 from consulting any previous file). And then below that,
 exceptions to the defined universal policies. You can regard
 <TT
CLASS="FILENAME"
>user.action</TT
> as an appendix to <TT
CLASS="FILENAME"
>default.action</TT
>,
 with the advantage that it is a separate file, which makes preserving your
 personal settings across <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> upgrades easier.</P
><P
> 
 Actions can be used to block anything you want, including ads, banners, or
 just some obnoxious URL whose content you would rather not see. Cookies can be accepted
 or rejected, or accepted only during the current browser session (i.e. not
 written to disk), content can be modified, some JavaScripts tamed, user-tracking
 fooled, and much more. See below for a <A
HREF="actions-file.html#ACTIONS"
>complete list
 of actions</A
>.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN2442"
>8.1. Finding the Right Mix</A
></H2
><P
> Note that some <A
HREF="actions-file.html#ACTIONS"
>actions</A
>, like cookie suppression
 or script disabling, may render some sites unusable that rely on these
 techniques to work properly. Finding the right mix of actions is not always easy and
 certainly a matter of personal taste. And, things can always change, requiring 
 refinements in the configuration. In general, it can be said that the more
 <SPAN
CLASS="QUOTE"
>"aggressive"</SPAN
> your default settings (in the top section of the
 actions file) are, the more exceptions for <SPAN
CLASS="QUOTE"
>"trusted"</SPAN
> sites you
 will have to make later. If, for example, you want to crunch all cookies per
 default, you'll have to make exceptions from that rule for sites that you
 regularly use and that require cookies for actually useful purposes, like maybe
 your bank, favorite shop, or newspaper.</P
><P
> We have tried to provide you with reasonable rules to start from in the
 distribution actions files. But there is no general rule of thumb on these
 things. There just are too many variables, and sites are constantly changing.
 Sooner or later you will want to change the rules (and read this chapter again :).</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN2449"
>8.2. How to Edit</A
></H2
><P
> The easiest way to edit the actions files is with a browser by
 using our browser-based editor, which can be reached from <A
HREF="http://config.privoxy.org/show-status"
TARGET="_top"
>http://config.privoxy.org/show-status</A
>.
 Note: the config file option <A
HREF="config.html#ENABLE-EDIT-ACTIONS"
>enable-edit-actions</A
> must be enabled for
 this to work. The editor allows both fine-grained control over every single
 feature on a per-URL basis, and easy choosing from wholesale sets of defaults
 like <SPAN
CLASS="QUOTE"
>"Cautious"</SPAN
>, <SPAN
CLASS="QUOTE"
>"Medium"</SPAN
> or
 <SPAN
CLASS="QUOTE"
>"Advanced"</SPAN
>. Warning: the <SPAN
CLASS="QUOTE"
>"Advanced"</SPAN
> setting is more
 aggressive, and will be more likely to cause problems for some sites.
 Experienced users only! 
 </P
><P
> If you prefer plain text editing to GUIs, you can of course also directly edit the
 the actions files with your favorite text editor. Look at
 <TT
CLASS="FILENAME"
>default.action</TT
> which is richly commented with many 
 good examples.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="ACTIONS-APPLY"
>8.3. How Actions are Applied to Requests</A
></H2
><P
> Actions files are divided into sections. There are special sections,
 like the <SPAN
CLASS="QUOTE"
>"<A
HREF="actions-file.html#ALIASES"
>alias</A
>"</SPAN
> sections which will
 be discussed later. For now let's concentrate on regular sections: They have a
 heading line (often split up to multiple lines for readability) which consist
 of a list of actions, separated by whitespace and enclosed in curly braces.
 Below that, there is a list of URL and tag patterns, each on a separate line.</P
><P
> To determine which actions apply to a request, the URL of the request is
 compared to all URL patterns in each <SPAN
CLASS="QUOTE"
>"action file"</SPAN
>.
 Every time it matches, the list of applicable actions for the request is
 incrementally updated, using the heading of the section in which the
 pattern is located. The same is done again for tags and tag patterns later on.</P
><P
> If multiple applying sections set the same action differently,
 the last match wins. If not, the effects are aggregated.
 E.g. a URL might match a regular section with a heading line of <TT
CLASS="LITERAL"
>{ 
 +<A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
> }</TT
>,
 then later another one with just <TT
CLASS="LITERAL"
>{
 +<A
HREF="actions-file.html#BLOCK"
>block</A
> }</TT
>, resulting
 in <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>both</I
></SPAN
> actions to apply. And there may well be 
 cases where you will want to combine actions together. Such a section then 
 might look like:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>  { +<TT
CLASS="LITERAL"
>handle-as-image</TT
>  +<TT
CLASS="LITERAL"
>block{Banner ads.}</TT
> }
  # Block these as if they were images. Send no block page.
   banners.example.com
   media.example.com/.*banners
   .example.com/images/ads/</PRE
></TD
></TR
></TABLE
>
 </P
><P
> You can trace this process for URL patterns and any given URL by visiting <A
HREF="http://config.privoxy.org/show-url-info"
TARGET="_top"
>http://config.privoxy.org/show-url-info</A
>.</P
><P
> Examples and more detail on this is provided in the Appendix, <A
HREF="appendix.html#ACTIONSANAT"
> Troubleshooting: Anatomy of an Action</A
> section.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AF-PATTERNS"
>8.4. Patterns</A
></H2
><P
> 
 As mentioned, <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> uses <SPAN
CLASS="QUOTE"
>"patterns"</SPAN
>
 to determine what <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>actions</I
></SPAN
> might apply to which sites and
 pages your browser attempts to access. These <SPAN
CLASS="QUOTE"
>"patterns"</SPAN
> use wild
 card type <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>pattern</I
></SPAN
> matching to achieve a high degree of
 flexibility. This allows one expression to be expanded and potentially match
 against many similar patterns.</P
><P
> Generally, an URL pattern has the form
 <TT
CLASS="LITERAL"
>&#60;domain&#62;&#60;port&#62;/&#60;path&#62;</TT
>, where the
 <TT
CLASS="LITERAL"
>&#60;domain&#62;</TT
>, the <TT
CLASS="LITERAL"
>&#60;port&#62;</TT
>
 and the <TT
CLASS="LITERAL"
>&#60;path&#62;</TT
> are optional. (This is why the special
 <TT
CLASS="LITERAL"
>/</TT
> pattern matches all URLs). Note that the protocol
 portion of the URL pattern (e.g. <TT
CLASS="LITERAL"
>http://</TT
>) should
 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> be included in the pattern. This is assumed already!</P
><P
> The pattern matching syntax is different for the domain and path parts of
 the URL. The domain part uses a simple globbing type matching technique, 
 while the path part uses more flexible 
 <A
HREF="http://en.wikipedia.org/wiki/Regular_expressions"
TARGET="_top"
><SPAN
CLASS="QUOTE"
>"Regular
  Expressions"</SPAN
></A
> (POSIX 1003.2).</P
><P
> The port part of a pattern is a decimal port number preceded by a colon
 (<TT
CLASS="LITERAL"
>:</TT
>). If the domain part contains a numerical IPv6 address,
 it has to be put into angle brackets
 (<TT
CLASS="LITERAL"
>&#60;</TT
>, <TT
CLASS="LITERAL"
>&#62;</TT
>).</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>www.example.com/</TT
></DT
><DD
><P
>    is a domain-only pattern and will match any request to <TT
CLASS="LITERAL"
>www.example.com</TT
>,
    regardless of which document on that server is requested. So ALL pages in
    this domain would be covered by the scope of this action. Note that a 
    simple <TT
CLASS="LITERAL"
>example.com</TT
> is different and would NOT match.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>www.example.com</TT
></DT
><DD
><P
>    means exactly the same. For domain-only patterns, the trailing <TT
CLASS="LITERAL"
>/</TT
> may
    be omitted.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>www.example.com/index.html</TT
></DT
><DD
><P
>    matches all the documents on <TT
CLASS="LITERAL"
>www.example.com</TT
>
    whose name starts with <TT
CLASS="LITERAL"
>/index.html</TT
>.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>www.example.com/index.html$</TT
></DT
><DD
><P
>    matches only the single document <TT
CLASS="LITERAL"
>/index.html</TT
>
    on <TT
CLASS="LITERAL"
>www.example.com</TT
>.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>/index.html$</TT
></DT
><DD
><P
>    matches the document <TT
CLASS="LITERAL"
>/index.html</TT
>, regardless of the domain,
    i.e. on <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>any</I
></SPAN
> web server anywhere.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>:8000/</TT
></DT
><DD
><P
>    Matches any URL pointing to TCP port 8000.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>&#60;2001:db8::1&#62;/</TT
></DT
><DD
><P
>    Matches any URL with the host address <TT
CLASS="LITERAL"
>2001:db8::1</TT
>.
    (Note that the real URL uses plain brackets, not angle brackets.)
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>index.html</TT
></DT
><DD
><P
>    matches nothing, since it would be interpreted as a domain name and
    there is no top-level domain called <TT
CLASS="LITERAL"
>.html</TT
>. So its 
    a mistake.
   </P
></DD
></DL
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN2556"
>8.4.1. The Domain Pattern</A
></H3
><P
> The matching of the domain part offers some flexible options: if the
 domain starts or ends with a dot, it becomes unanchored at that end. 
 For example:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>.example.com</TT
></DT
><DD
><P
>    matches any domain with first-level domain <TT
CLASS="LITERAL"
>com</TT
>
    and second-level domain <TT
CLASS="LITERAL"
>example</TT
>.
    For example <TT
CLASS="LITERAL"
>www.example.com</TT
>,
    <TT
CLASS="LITERAL"
>example.com</TT
> and <TT
CLASS="LITERAL"
>foo.bar.baz.example.com</TT
>.
    Note that it wouldn't match if the second-level domain was <TT
CLASS="LITERAL"
>another-example</TT
>.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>www.</TT
></DT
><DD
><P
>    matches any domain that <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>STARTS</I
></SPAN
> with
    <TT
CLASS="LITERAL"
>www.</TT
> (It also matches the domain
    <TT
CLASS="LITERAL"
>www</TT
> but most of the time that doesn't matter.)
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.example.</TT
></DT
><DD
><P
>    matches any domain that <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>CONTAINS</I
></SPAN
> <TT
CLASS="LITERAL"
>.example.</TT
>.
    And, by the way, also included would be any files or documents that exist
    within that domain since no path limitations are specified. (Correctly
    speaking: It matches any FQDN that contains <TT
CLASS="LITERAL"
>example</TT
> as
    a domain.) This might be <TT
CLASS="LITERAL"
>www.example.com</TT
>,
    <TT
CLASS="LITERAL"
>news.example.de</TT
>, or
    <TT
CLASS="LITERAL"
>www.example.net/cgi/testing.pl</TT
> for instance. All these
    cases are matched. 
   </P
></DD
></DL
></DIV
><P
> Additionally, there are wild-cards that you can use in the domain names
 themselves. These work similarly to shell globbing type wild-cards:
 <SPAN
CLASS="QUOTE"
>"*"</SPAN
> represents zero or more arbitrary characters (this is
 equivalent to the 
 <A
HREF="http://en.wikipedia.org/wiki/Regular_expressions"
TARGET="_top"
><SPAN
CLASS="QUOTE"
>"Regular
 Expression"</SPAN
></A
> based syntax of <SPAN
CLASS="QUOTE"
>".*"</SPAN
>),
 <SPAN
CLASS="QUOTE"
>"?"</SPAN
>  represents any single character (this is equivalent to the
 regular expression syntax of a simple <SPAN
CLASS="QUOTE"
>"."</SPAN
>), and you can define
 <SPAN
CLASS="QUOTE"
>"character classes"</SPAN
> in square brackets which is similar to 
 the same regular expression technique. All of this can be freely mixed:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>ad*.example.com</TT
></DT
><DD
><P
>    matches <SPAN
CLASS="QUOTE"
>"adserver.example.com"</SPAN
>, 
    <SPAN
CLASS="QUOTE"
>"ads.example.com"</SPAN
>, etc but not <SPAN
CLASS="QUOTE"
>"sfads.example.com"</SPAN
>
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>*ad*.example.com</TT
></DT
><DD
><P
>    matches all of the above, and then some.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.?pix.com</TT
></DT
><DD
><P
>    matches <TT
CLASS="LITERAL"
>www.ipix.com</TT
>,
    <TT
CLASS="LITERAL"
>pictures.epix.com</TT
>, <TT
CLASS="LITERAL"
>a.b.c.d.e.upix.com</TT
> etc. 
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>www[1-9a-ez].example.c*</TT
></DT
><DD
><P
>     matches <TT
CLASS="LITERAL"
>www1.example.com</TT
>, 
     <TT
CLASS="LITERAL"
>www4.example.cc</TT
>, <TT
CLASS="LITERAL"
>wwwd.example.cy</TT
>, 
     <TT
CLASS="LITERAL"
>wwwz.example.com</TT
> etc., but <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> 
     <TT
CLASS="LITERAL"
>wwww.example.com</TT
>.
   </P
></DD
></DL
></DIV
><P
> While flexible, this is not the sophistication of full regular expression based syntax.</P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN2632"
>8.4.2. The Path Pattern</A
></H3
><P
> <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> uses <SPAN
CLASS="QUOTE"
>"modern"</SPAN
> POSIX 1003.2
  <A
HREF="http://en.wikipedia.org/wiki/Regular_expressions"
TARGET="_top"
><SPAN
CLASS="QUOTE"
>"Regular
  Expressions"</SPAN
></A
> for matching the path portion (after the slash),
  and is thus more flexible.</P
><P
> There is an <A
HREF="appendix.html#REGEX"
>Appendix</A
> with a brief quick-start into regular
 expressions, you also might want to have a look at your operating system's documentation
 on regular expressions (try <TT
CLASS="LITERAL"
>man re_format</TT
>).</P
><P
> Note that the path pattern is automatically left-anchored at the <SPAN
CLASS="QUOTE"
>"/"</SPAN
>,
 i.e. it matches as if it would start with a <SPAN
CLASS="QUOTE"
>"^"</SPAN
> (regular expression speak 
 for the beginning of a line).</P
><P
> Please also note that matching in the path is <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>CASE INSENSITIVE</I
></SPAN
>
 by default, but you can switch to case sensitive at any point in the pattern by using the 
 <SPAN
CLASS="QUOTE"
>"(?-i)"</SPAN
> switch: <TT
CLASS="LITERAL"
>www.example.com/(?-i)PaTtErN.*</TT
> will match
 only documents whose path starts with <TT
CLASS="LITERAL"
>PaTtErN</TT
> in
 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>exactly</I
></SPAN
> this capitalization.</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>.example.com/.*</TT
></DT
><DD
><P
>     Is equivalent to just <SPAN
CLASS="QUOTE"
>".example.com"</SPAN
>, since any documents 
     within that domain are matched with or without the <SPAN
CLASS="QUOTE"
>".*"</SPAN
>
     regular expression. This is redundant
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.example.com/.*/index.html$</TT
></DT
><DD
><P
>    Will match any page in the domain of <SPAN
CLASS="QUOTE"
>"example.com"</SPAN
> that is
    named <SPAN
CLASS="QUOTE"
>"index.html"</SPAN
>, and that is part of some path. For
    example, it matches <SPAN
CLASS="QUOTE"
>"www.example.com/testing/index.html"</SPAN
> but
    NOT <SPAN
CLASS="QUOTE"
>"www.example.com/index.html"</SPAN
> because the regular
    expression called for at least two <SPAN
CLASS="QUOTE"
>"/'s"</SPAN
>, thus the path 
    requirement. It also would match 
    <SPAN
CLASS="QUOTE"
>"www.example.com/testing/index_html"</SPAN
>, because of the 
    special meta-character <SPAN
CLASS="QUOTE"
>"."</SPAN
>.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.example.com/(.*/)?index\.html$</TT
></DT
><DD
><P
>    This regular expression is conditional so it will match any page 
    named <SPAN
CLASS="QUOTE"
>"index.html"</SPAN
> regardless of path which in this case can 
    have one or more <SPAN
CLASS="QUOTE"
>"/'s"</SPAN
>. And this one must contain exactly 
    <SPAN
CLASS="QUOTE"
>".html"</SPAN
> (but does not have to end with that!).
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.example.com/(.*/)(ads|banners?|junk)</TT
></DT
><DD
><P
>    This regular expression will match any path of <SPAN
CLASS="QUOTE"
>"example.com"</SPAN
>
    that contains any of the words <SPAN
CLASS="QUOTE"
>"ads"</SPAN
>, <SPAN
CLASS="QUOTE"
>"banner"</SPAN
>, 
    <SPAN
CLASS="QUOTE"
>"banners"</SPAN
> (because of the <SPAN
CLASS="QUOTE"
>"?"</SPAN
>) or <SPAN
CLASS="QUOTE"
>"junk"</SPAN
>.
    The path does not have to end in these words, just contain them.
   </P
></DD
><DT
><TT
CLASS="LITERAL"
>.example.com/(.*/)(ads|banners?|junk)/.*\.(jpe?g|gif|png)$</TT
></DT
><DD
><P
>    This is very much the same as above, except now it must end in either 
    <SPAN
CLASS="QUOTE"
>".jpg"</SPAN
>, <SPAN
CLASS="QUOTE"
>".jpeg"</SPAN
>, <SPAN
CLASS="QUOTE"
>".gif"</SPAN
> or <SPAN
CLASS="QUOTE"
>".png"</SPAN
>. So this 
    one is limited to common image formats.
   </P
></DD
></DL
></DIV
><P
> There are many, many good examples to be found in <TT
CLASS="FILENAME"
>default.action</TT
>, 
 and more tutorials below in <A
HREF="appendix.html#REGEX"
>Appendix on regular expressions</A
>.</P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="TAG-PATTERN"
>8.4.3. The Tag Pattern</A
></H3
><P
> Tag patterns are used to change the applying actions based on the
 request's tags. Tags can be created with either the
 <A
HREF="actions-file.html#CLIENT-HEADER-TAGGER"
>client-header-tagger</A
>
 or the  <A
HREF="actions-file.html#SERVER-HEADER-TAGGER"
>server-header-tagger</A
> action.</P
><P
> Tag patterns have to start with <SPAN
CLASS="QUOTE"
>"TAG:"</SPAN
>, so <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
 can tell them apart from URL patterns. Everything after the colon
 including white space, is interpreted as a regular expression with
 path pattern syntax, except that tag patterns aren't left-anchored
 automatically (<SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> doesn't silently add a <SPAN
CLASS="QUOTE"
>"^"</SPAN
>,
 you have to do it yourself if you need it).</P
><P
> To match all requests that are tagged with <SPAN
CLASS="QUOTE"
>"foo"</SPAN
>
 your pattern line should be <SPAN
CLASS="QUOTE"
>"TAG:^foo$"</SPAN
>,
 <SPAN
CLASS="QUOTE"
>"TAG:foo"</SPAN
> would work as well, but it would also
 match requests whose tags contain <SPAN
CLASS="QUOTE"
>"foo"</SPAN
> somewhere.
 <SPAN
CLASS="QUOTE"
>"TAG: foo"</SPAN
> wouldn't work as it requires white space.</P
><P
> Sections can contain URL and tag patterns at the same time,
 but tag patterns are checked after the URL patterns and thus
 always overrule them, even if they are located before the URL patterns.</P
><P
> Once a new tag is added, Privoxy checks right away if it's matched by one
 of the tag patterns and updates the action settings accordingly. As a result
 tags can be used to activate other tagger actions, as long as these other
 taggers look for headers that haven't already be parsed.</P
><P
> For example you could tag client requests which use the
 <TT
CLASS="LITERAL"
>POST</TT
> method,
 then use this tag to activate another tagger that adds a tag if cookies
 are sent, and then use a block action based on the cookie tag. This allows
 the outcome of one action, to be input into a subsequent action. However if
 you'd reverse the position of the described taggers, and activated the
 method tagger based on the cookie tagger, no method tags would be created.
 The method tagger would look for the request line, but at the time
 the cookie tag is created, the request line has already been parsed.</P
><P
> While this is a limitation you should be aware of, this kind of
 indirection is seldom needed anyway and even the example doesn't
 make too much sense.</P
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="ACTIONS"
>8.5. Actions</A
></H2
><P
> All actions are disabled by default, until they are explicitly enabled
 somewhere in an actions file. Actions are turned on if preceded with a
 <SPAN
CLASS="QUOTE"
>"+"</SPAN
>, and turned off if preceded with a <SPAN
CLASS="QUOTE"
>"-"</SPAN
>. So a
 <TT
CLASS="LITERAL"
>+action</TT
> means <SPAN
CLASS="QUOTE"
>"do that action"</SPAN
>, e.g.
 <TT
CLASS="LITERAL"
>+block</TT
> means <SPAN
CLASS="QUOTE"
>"please block URLs that match the
 following patterns"</SPAN
>, and <TT
CLASS="LITERAL"
>-block</TT
> means <SPAN
CLASS="QUOTE"
>"don't
 block URLs that match the following patterns, even if <TT
CLASS="LITERAL"
>+block</TT
>
 previously applied."</SPAN
>&#13;</P
><P
> 
 Again, actions are invoked by placing them on a line, enclosed in curly braces and
 separated by whitespace, like in 
 <TT
CLASS="LITERAL"
>{+some-action -some-other-action{some-parameter}}</TT
>,
 followed by a list of URL patterns, one per line, to which they apply.
 Together, the actions line and the following pattern lines make up a section
 of the actions file. </P
><P
> 
 Actions fall into three categories:</P
><P
> <P
></P
><UL
><LI
><P
>  
   Boolean, i.e the action can only be <SPAN
CLASS="QUOTE"
>"enabled"</SPAN
> or
   <SPAN
CLASS="QUOTE"
>"disabled"</SPAN
>. Syntax:
  </P
><P
>   <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>  +<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>        # enable action <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
  -<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>        # disable action <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></PRE
></TD
></TR
></TABLE
>
  </P
><P
>  
   Example: <TT
CLASS="LITERAL"
>+handle-as-image</TT
>
  </P
></LI
><LI
><P
>  
   Parameterized, where some value is required in order to enable this type of action.
   Syntax:
  </P
><P
>   <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>  +<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>{<TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
>}  # enable action and set parameter to <TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
>,
               # overwriting parameter from previous match if necessary
  -<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>         # disable action. The parameter can be omitted</PRE
></TD
></TR
></TABLE
>
  </P
><P
>   Note that if the URL matches multiple positive forms of a parameterized action,
   the last match wins, i.e. the params from earlier matches are simply ignored.
  </P
><P
>  
   Example: <TT
CLASS="LITERAL"
>+hide-user-agent{Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.1.4) Gecko/20070602 Firefox/2.0.0.4}</TT
>
  </P
></LI
><LI
><P
>  
   Multi-value. These look exactly like parameterized actions,
   but they behave differently: If the action applies multiple times to the
   same URL, but with different parameters, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> the parameters
   from <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> matches are remembered. This is used for actions
   that can be executed for the same request repeatedly, like adding multiple
   headers, or filtering through multiple filters. Syntax:
  </P
><P
>   <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>  +<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>{<TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
>}   # enable action and add <TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
> to the list of parameters
  -<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>{<TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
>}   # remove the parameter <TT
CLASS="REPLACEABLE"
><I
>param</I
></TT
> from the list of parameters
                # If it was the last one left, disable the action.
  <TT
CLASS="REPLACEABLE"
><I
>-name</I
></TT
>          # disable this action completely and remove all parameters from the list</PRE
></TD
></TR
></TABLE
>
  </P
><P
>  
   Examples: <TT
CLASS="LITERAL"
>+add-header{X-Fun-Header: Some text}</TT
> and
   <TT
CLASS="LITERAL"
>+filter{html-annoyances}</TT
>
  </P
></LI
></UL
></P
><P
> If nothing is specified in any actions file, no <SPAN
CLASS="QUOTE"
>"actions"</SPAN
> are
 taken. So in this case <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> would just be a
 normal, non-blocking, non-filtering proxy. You must specifically enable the
 privacy and blocking features you need (although the provided default actions
 files will give a good starting point).</P
><P
> Later defined action sections always over-ride earlier ones of the same type.
 So exceptions to any rules you make, should come in the latter part of the file (or 
 in a file that is processed later when using multiple actions files such 
 as <TT
CLASS="FILENAME"
>user.action</TT
>). For multi-valued actions, the actions
 are applied in the order they are specified. Actions files are processed in
 the order they are defined in <TT
CLASS="FILENAME"
>config</TT
> (the default
 installation has three actions files). It also quite possible for any given
 URL to match more than one <SPAN
CLASS="QUOTE"
>"pattern"</SPAN
> (because of wildcards and
 regular expressions), and thus to trigger more than one set of actions! Last
 match wins.</P
><P
> The list of valid <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> actions are:</P
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="ADD-HEADER"
>8.5.1. add-header</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Confuse log analysis, custom applications</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Sends a user defined HTTP header to the web server.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Multi-value.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Any string value is possible. Validity of the defined HTTP headers is not checked.
    It is recommended that you use the <SPAN
CLASS="QUOTE"
>"<TT
CLASS="LITERAL"
>X-</TT
>"</SPAN
> prefix
    for custom headers.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This action may be specified multiple times, in order to define multiple 
    headers. This is rarely needed for the typical user. If you don't know what 
    <SPAN
CLASS="QUOTE"
>"HTTP headers"</SPAN
> are, you definitely don't need to worry about this 
    one.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+add-header{X-User-Tracking: sucks}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="BLOCK"
>8.5.2. block</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Block ads or other unwanted content</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Requests for URLs to which this action applies are blocked, i.e. the
    requests are trapped by <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> and the requested URL is never retrieved,
    but is answered locally with a substitute page or image, as determined by
    the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
></TT
>,
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker</A
></TT
>, and 
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HANDLE-AS-EMPTY-DOCUMENT"
>handle-as-empty-document</A
></TT
> actions.
    
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>A block reason that should be given to the user.</P
></DD
><DT
>Notes:</DT
><DD
><P
>    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> sends a special <SPAN
CLASS="QUOTE"
>"BLOCKED"</SPAN
> page
    for requests to blocked pages. This page contains the block reason given as
    parameter, a link to find out why the block action applies, and a click-through
    to the blocked content (the latter only if the force feature is available and
    enabled).
   </P
><P
> 
    A very important exception occurs if <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>both</I
></SPAN
> 
    <TT
CLASS="LITERAL"
>block</TT
> and <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
></TT
>,
    apply to the same request: it will then be replaced by an image. If 
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker</A
></TT
>
    (see below) also applies, the type of image will be determined by its parameter,
    if not, the standard checkerboard pattern is sent.
   </P
><P
>    It is important to understand this process, in order 
    to understand how <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> deals with 
    ads and other unwanted content. Blocking is a core feature, and one 
    upon which various other features depend.
   </P
><P
>    The <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER"
>filter</A
></TT
>
    action can perform a very similar task, by <SPAN
CLASS="QUOTE"
>"blocking"</SPAN
>
    banner images and other content through rewriting the relevant URLs in the
    document's HTML source, so they don't get requested in the first place.
    Note that this is a totally different technique, and it's easy to confuse the two.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{+block{No nasty stuff for you.}}
# Block and replace with "blocked" page
 .nasty-stuff.example.com

{+block{Doubleclick banners.} +handle-as-image} 
# Block and replace with image
 .ad.doubleclick.net
 .ads.r.us/banners/

{+block{Layered ads.} +handle-as-empty-document} 
# Block and then ignore
 adserver.example.net/.*\.js$</PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CHANGE-X-FORWARDED-FOR"
>8.5.3. change-x-forwarded-for</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Improve privacy by not forwarding the source of the request in the HTTP headers.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"X-Forwarded-For:"</SPAN
> HTTP header from the client request,
    or adds a new one.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
></P
><UL
><LI
><P
><SPAN
CLASS="QUOTE"
>"block"</SPAN
> to delete the header.</P
></LI
><LI
><P
>       <SPAN
CLASS="QUOTE"
>"add"</SPAN
> to create the header (or append
       the client's IP address to an already existing one).
     </P
></LI
></UL
></DD
><DT
>Notes:</DT
><DD
><P
>    It is safe and recommended to use <TT
CLASS="LITERAL"
>block</TT
>.
   </P
><P
>    Forwarding the source address of the request may make
    sense in some multi-user setups but is also a privacy risk.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+change-x-forwarded-for{block}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CLIENT-HEADER-FILTER"
>8.5.4. client-header-filter</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>   Rewrite or remove single client headers.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    All client headers to which this action applies are filtered on-the-fly through
    the specified regular expression based substitutions.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    The name of a client-header filter, as defined in one of the
    <A
HREF="filter-file.html"
>filter files</A
>.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Client-header filters are applied to each header on its own, not to
    all at once. This makes it easier to diagnose problems, but on the downside
    you can't write filters that only change header x if header y's value is z.
    You can do that by using tags though.
   </P
><P
>    Client-header filters are executed after the other header actions have finished
    and use their output as input.
   </P
><P
>    If the request URL gets changed, <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> will detect that and use the new
    one. This can be used to rewrite the request destination behind the client's
    back, for example to specify a Tor exit relay for certain requests.
   </P
><P
>    Please refer to the <A
HREF="filter-file.html"
>filter file chapter</A
>
    to learn which client-header filters are available by default, and how to
    create your own.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Hide Tor exit notation in Host and Referer Headers
{+client-header-filter{hide-tor-exit-notation}}
/
    </PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CLIENT-HEADER-TAGGER"
>8.5.5. client-header-tagger</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>   Block requests based on their headers.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Client headers to which this action applies are filtered on-the-fly through
    the specified regular expression based substitutions, the result is used as
    tag. 
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    The name of a client-header tagger, as defined in one of the
    <A
HREF="filter-file.html"
>filter files</A
>.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Client-header taggers are applied to each header on its own,
    and as the header isn't modified, each tagger <SPAN
CLASS="QUOTE"
>"sees"</SPAN
>
    the original.
   </P
><P
>    Client-header taggers are the first actions that are executed
    and their tags can be used to control every other action.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Tag every request with the User-Agent header
{+client-header-tagger{user-agent}}
/

# Tagging itself doesn't change the action
# settings, sections with TAG patterns do:
#
# If it's a download agent, use a different forwarding proxy,
# show the real User-Agent and make sure resume works.
{+forward-override{forward-socks5 10.0.0.2:2222 .} \
 -hide-if-modified-since      \
 -overwrite-last-modified     \
 -hide-user-agent             \
 -filter                      \
 -deanimate-gifs              \
}
TAG:^User-Agent: NetBSD-ftp/
TAG:^User-Agent: Novell ZYPP Installer
TAG:^User-Agent: RPM APT-HTTP/
TAG:^User-Agent: fetch libfetch/
TAG:^User-Agent: Ubuntu APT-HTTP/
TAG:^User-Agent: MPlayer/
    </PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CONTENT-TYPE-OVERWRITE"
>8.5.6. content-type-overwrite</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Stop useless download menus from popping up, or change the browser's rendering mode</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Replaces the <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> HTTP server header.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Any string. 
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    The <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> HTTP server header is used by the
    browser to decide what to do with the document. The value of this
    header can cause the browser to open a download menu instead of
    displaying the document by itself, even if the document's format is
    supported by the browser. 
   </P
><P
>    The declared content type can also affect which rendering mode
    the browser chooses. If XHTML is delivered as <SPAN
CLASS="QUOTE"
>"text/html"</SPAN
>,
    many browsers treat it as yet another broken HTML document.
    If it is send as <SPAN
CLASS="QUOTE"
>"application/xml"</SPAN
>, browsers with
    XHTML support will only display it, if the syntax is correct.
   </P
><P
>    If you see a web site that proudly uses XHTML buttons, but sets
    <SPAN
CLASS="QUOTE"
>"Content-Type: text/html"</SPAN
>, you can use <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
    to overwrite it with <SPAN
CLASS="QUOTE"
>"application/xml"</SPAN
> and validate
    the web master's claim inside your XHTML-supporting browser.
    If the syntax is incorrect, the browser will complain loudly. 
   </P
><P
>    You can also go the opposite direction: if your browser prints
    error messages instead of rendering a document falsely declared
    as XHTML, you can overwrite the content type with
    <SPAN
CLASS="QUOTE"
>"text/html"</SPAN
> and have it rendered as broken HTML document. 
   </P
><P
>    By default <TT
CLASS="LITERAL"
>content-type-overwrite</TT
> only replaces
    <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> headers that look like some kind of text.
    If you want to overwrite it unconditionally, you have to combine it with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FORCE-TEXT-MODE"
>force-text-mode</A
></TT
>.
    This limitation exists for a reason, think twice before circumventing it.
   </P
><P
>    Most of the time it's easier to replace this action with a custom
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SERVER-HEADER-FILTER"
>server-header filter</A
></TT
>.
    It allows you to activate it for every document of a certain site and it will still
    only replace the content types you aimed at.
   </P
><P
>    Of course you can apply <TT
CLASS="LITERAL"
>content-type-overwrite</TT
>
    to a whole site and then make URL based exceptions, but it's a lot
    more work to get the same precision. 
   </P
></DD
><DT
>Example usage (sections):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Check if www.example.net/ really uses valid XHTML
{ +content-type-overwrite{application/xml} }
www.example.net/

# but leave the content type unmodified if the URL looks like a style sheet
{-content-type-overwrite}
www.example.net/.*\.css$
www.example.net/.*style</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CRUNCH-CLIENT-HEADER"
>8.5.7. crunch-client-header</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Remove a client header <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> has no dedicated action for.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes every header sent by the client that contains the string the user supplied as parameter.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Any string.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This action allows you to block client headers for which no dedicated
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> action exists.
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> will remove every client header that
    contains the string you supplied as parameter.
   </P
><P
>    Regular expressions are <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not supported</I
></SPAN
> and you can't
    use this action to block different headers in the same request, unless
    they contain the same string.
   </P
><P
>    <TT
CLASS="LITERAL"
>crunch-client-header</TT
> is only meant for quick tests.
    If you have to block several different headers, or only want to modify
    parts of them, you should use a
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CLIENT-HEADER-FILTER"
>client-header filter</A
></TT
>.
   </P
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>      Don't block any header without understanding the consequences.
     </P
></TD
></TR
></TABLE
></DIV
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Block the non-existent "Privacy-Violation:" client header 
{ +crunch-client-header{Privacy-Violation:} }
/
    </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CRUNCH-IF-NONE-MATCH"
>8.5.8. crunch-if-none-match</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Prevent yet another way to track the user's steps between sessions.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"If-None-Match:"</SPAN
> HTTP client header.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Removing the <SPAN
CLASS="QUOTE"
>"If-None-Match:"</SPAN
> HTTP client header
    is useful for filter testing, where you want to force a real
    reload instead of getting status code <SPAN
CLASS="QUOTE"
>"304"</SPAN
> which
    would cause the browser to use a cached copy of the page.
   </P
><P
>    It is also useful to make sure the header isn't used as a cookie
    replacement (unlikely but possible).
   </P
><P
>    Blocking the <SPAN
CLASS="QUOTE"
>"If-None-Match:"</SPAN
> header shouldn't cause any
    caching problems, as long as the <SPAN
CLASS="QUOTE"
>"If-Modified-Since:"</SPAN
> header
    isn't blocked or missing as well.
   </P
><P
>    It is recommended to use this action together with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HIDE-IF-MODIFIED-SINCE"
>hide-if-modified-since</A
></TT
>
    and
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#OVERWRITE-LAST-MODIFIED"
>overwrite-last-modified</A
></TT
>.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Let the browser revalidate cached documents but don't
# allow the server to use the revalidation headers for user tracking.
{+hide-if-modified-since{-60} \
 +overwrite-last-modified{randomize} \
 +crunch-if-none-match}
/   </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CRUNCH-INCOMING-COOKIES"
>8.5.9. crunch-incoming-cookies</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>    Prevent the web server from setting HTTP cookies on your system
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes any <SPAN
CLASS="QUOTE"
>"Set-Cookie:"</SPAN
> HTTP headers from server replies.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This action is only concerned with <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>incoming</I
></SPAN
> HTTP cookies. For
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>outgoing</I
></SPAN
> HTTP cookies, use
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
></TT
>.
    Use <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>both</I
></SPAN
> to disable HTTP cookies completely.
   </P
><P
>    It makes <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>no sense at all</I
></SPAN
> to use this action in conjunction
    with the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SESSION-COOKIES-ONLY"
>session-cookies-only</A
></TT
> action,
    since it would prevent the session cookies from being set. See also 
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER-CONTENT-COOKIES"
>filter-content-cookies</A
></TT
>.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+crunch-incoming-cookies</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CRUNCH-SERVER-HEADER"
>8.5.10. crunch-server-header</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Remove a server header <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> has no dedicated action for.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes every header sent by the server that contains the string the user supplied as parameter.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Any string.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This action allows you to block server headers for which no dedicated
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> action exists. <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
    will remove every server header that contains the string you supplied as parameter.
   </P
><P
>    Regular expressions are <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not supported</I
></SPAN
> and you can't
    use this action to block different headers in the same request, unless
    they contain the same string.
   </P
><P
>    <TT
CLASS="LITERAL"
>crunch-server-header</TT
> is only meant for quick tests.
    If you have to block several different headers, or only want to modify
    parts of them, you should use a custom
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SERVER-HEADER-FILTER"
>server-header filter</A
></TT
>.
   </P
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>     Don't block any header without understanding the consequences.
     </P
></TD
></TR
></TABLE
></DIV
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Crunch server headers that try to prevent caching
{ +crunch-server-header{no-cache} }
/   </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="CRUNCH-OUTGOING-COOKIES"
>8.5.11. crunch-outgoing-cookies</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>    Prevent the web server from reading any HTTP cookies from your system
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes any <SPAN
CLASS="QUOTE"
>"Cookie:"</SPAN
> HTTP headers from client requests.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This action is only concerned with <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>outgoing</I
></SPAN
> HTTP cookies. For
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>incoming</I
></SPAN
> HTTP cookies, use
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
></TT
>.
    Use <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>both</I
></SPAN
> to disable HTTP cookies completely.
   </P
><P
>    It makes <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>no sense at all</I
></SPAN
> to use this action in conjunction
    with the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SESSION-COOKIES-ONLY"
>session-cookies-only</A
></TT
> action,
    since it would prevent the session cookies from being read.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+crunch-outgoing-cookies</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="DEANIMATE-GIFS"
>8.5.12. deanimate-gifs</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Stop those annoying, distracting animated GIF images.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    De-animate GIF animations, i.e. reduce them to their first or last image.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    <SPAN
CLASS="QUOTE"
>"last"</SPAN
> or <SPAN
CLASS="QUOTE"
>"first"</SPAN
>
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This will also shrink the images considerably (in bytes, not pixels!). If
    the option <SPAN
CLASS="QUOTE"
>"first"</SPAN
> is given, the first frame of the animation
    is used as the replacement. If <SPAN
CLASS="QUOTE"
>"last"</SPAN
> is given, the last
    frame of the animation is used instead, which probably makes more sense for
    most banner animations, but also has the risk of not showing the entire
    last frame (if it is only a delta to an earlier frame).
   </P
><P
>    You can safely use this action with patterns that will also match non-GIF
    objects, because no attempt will be made at anything that doesn't look like
    a GIF.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>      <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+deanimate-gifs{last}</PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="DOWNGRADE-HTTP-VERSION"
>8.5.13. downgrade-http-version</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Work around (very rare) problems with HTTP/1.1</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Downgrades HTTP/1.1 client requests and server replies to HTTP/1.0.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This is a left-over from the time when <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
    didn't support important HTTP/1.1 features well. It is left here for the
    unlikely case that you experience HTTP/1.1 related problems with some server
    out there. Not all HTTP/1.1 features and requirements are supported yet,
    so there is a chance you might need this action.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{+downgrade-http-version}
problem-host.example.com</PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="FAST-REDIRECTS"
>8.5.14. fast-redirects</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Fool some click-tracking scripts and speed up indirect links.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Detects redirection URLs and redirects the browser without contacting
    the redirection server first.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
></P
><UL
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"simple-check"</SPAN
> to just search for the string <SPAN
CLASS="QUOTE"
>"http://"</SPAN
>
      to detect redirection URLs.
     </P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"check-decoded-url"</SPAN
> to decode URLs (if necessary) before searching
      for redirection URLs.
     </P
></LI
></UL
></DD
><DT
>Notes:</DT
><DD
><P
>  
    Many sites, like yahoo.com, don't just link to other sites. Instead, they
    will link to some script on their own servers, giving the destination as a
    parameter, which will then redirect you to the final target. URLs
    resulting from this scheme typically look like:
    <SPAN
CLASS="QUOTE"
>"http://www.example.org/click-tracker.cgi?target=http%3a//www.example.net/"</SPAN
>.
  </P
><P
>    Sometimes, there are even multiple consecutive redirects encoded in the
    URL. These redirections via scripts make your web browsing more traceable,
    since the server from which you follow such a link can see where you go
    to. Apart from that, valuable bandwidth and time is wasted, while your
    browser asks the server for one redirect after the other. Plus, it feeds
    the advertisers.
   </P
><P
>    This feature is currently not very smart and is scheduled for improvement.
    If it is enabled by default, you will have to create some exceptions to
    this action. It can lead to failures in several ways: 
   </P
><P
>    Not every URLs with other URLs as parameters is evil.
    Some sites offer a real service that requires this information to work.
    For example a validation service needs to know, which document to validate.
    <TT
CLASS="LITERAL"
>fast-redirects</TT
> assumes that every URL parameter that
    looks like another URL is a redirection target, and will always redirect to
    the last one. Most of the time the assumption is correct, but if it isn't,
    the user gets redirected anyway.
   </P
><P
>    Another failure occurs if the URL contains other parameters after the URL parameter.
    The URL:
    <SPAN
CLASS="QUOTE"
>"http://www.example.org/?redirect=http%3a//www.example.net/&#38;foo=bar"</SPAN
>.
    contains the redirection URL <SPAN
CLASS="QUOTE"
>"http://www.example.net/"</SPAN
>,
    followed by another parameter. <TT
CLASS="LITERAL"
>fast-redirects</TT
> doesn't know that
    and will cause a redirect to <SPAN
CLASS="QUOTE"
>"http://www.example.net/&#38;foo=bar"</SPAN
>.
    Depending on the target server configuration, the parameter will be silently ignored
    or lead to a <SPAN
CLASS="QUOTE"
>"page not found"</SPAN
> error. You can prevent this problem by
    first using the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#REDIRECT"
>redirect</A
></TT
> action
    to remove the last part of the URL, but it requires a little effort.
   </P
><P
>    To detect a redirection URL, <TT
CLASS="LITERAL"
>fast-redirects</TT
> only
    looks for the string <SPAN
CLASS="QUOTE"
>"http://"</SPAN
>, either in plain text
    (invalid but often used) or encoded as <SPAN
CLASS="QUOTE"
>"http%3a//"</SPAN
>.
    Some sites use their own URL encoding scheme, encrypt the address
    of the target server or replace it with a database id. In theses cases
    <TT
CLASS="LITERAL"
>fast-redirects</TT
> is fooled and the request reaches the
    redirection server where it probably gets logged.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
> { +fast-redirects{simple-check} }
   one.example.com 

 { +fast-redirects{check-decoded-url} }
   another.example.com/testing</PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="FILTER"
>8.5.15. filter</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Get rid of HTML and JavaScript annoyances, banner advertisements (by size), 
         do fun text replacements, add personalized effects, etc.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    All instances of text-based type, most notably HTML and JavaScript, to which
    this action applies, can be filtered on-the-fly through the specified regular
    expression based substitutions. (Note: as of version 3.0.3 plain text documents
    are exempted from filtering, because web servers often use the
   <TT
CLASS="LITERAL"
>text/plain</TT
> MIME type for all files whose type they don't know.)
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    The name of a content filter, as defined in the <A
HREF="filter-file.html"
>filter file</A
>.
    Filters can be defined in one or more  files as defined by the 
    <TT
CLASS="LITERAL"
><A
HREF="config.html#FILTERFILE"
>filterfile</A
></TT
>
    option in the <A
HREF="config.html"
>config file</A
>. 
    <TT
CLASS="FILENAME"
>default.filter</TT
> is the collection of filters 
    supplied by the developers. Locally defined filters should go 
    in their own file, such as <TT
CLASS="FILENAME"
>user.filter</TT
>.
   </P
><P
>     When used in its negative form,
     and without parameters, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> filtering is completely disabled.
  </P
></DD
><DT
>Notes:</DT
><DD
><P
>    For your convenience, there are a number of pre-defined filters available 
    in the distribution filter file that you can use. See the examples below for
    a list.
   </P
><P
>    Filtering requires buffering the page content, which may appear to
    slow down page rendering since nothing is displayed until all content has
    passed the filters. (It does not really take longer, but seems that way
    since the page is not incrementally displayed.) This effect will be more
    noticeable on slower connections.
   </P
><P
>   <SPAN
CLASS="QUOTE"
>"Rolling your own"</SPAN
>
    filters requires a knowledge of 
     <A
HREF="http://en.wikipedia.org/wiki/Regular_expressions"
TARGET="_top"
><SPAN
CLASS="QUOTE"
>"Regular
     Expressions"</SPAN
></A
> and 
      <A
HREF="http://en.wikipedia.org/wiki/Html"
TARGET="_top"
><SPAN
CLASS="QUOTE"
>"HTML"</SPAN
></A
>.
    This is very powerful feature, and potentially very intrusive. 
    Filters should be used with caution, and where an equivalent
    <SPAN
CLASS="QUOTE"
>"action"</SPAN
> is not available.
   </P
><P
>    The amount of data that can be filtered is limited to the 
    <TT
CLASS="LITERAL"
><A
HREF="config.html#BUFFER-LIMIT"
>buffer-limit</A
></TT
>
    option in the main <A
HREF="config.html"
>config file</A
>. The 
    default is 4096 KB (4 Megs). Once this limit is exceeded, the buffered
    data, and all pending data, is passed through unfiltered. 
   </P
><P
>    Inappropriate MIME types, such as zipped files, are not filtered at all.
    (Again, only text-based types except plain text). Encrypted SSL data
    (from HTTPS servers) cannot be filtered either, since this would violate
    the integrity of the secure transaction. In some situations it might
    be necessary to protect certain text, like source code, from filtering
    by defining appropriate <TT
CLASS="LITERAL"
>-filter</TT
> exceptions.
   </P
><P
>    Compressed content can't be filtered either, unless <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
    is compiled with zlib support (requires at least <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> 3.0.7),
    in which case <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> will decompress the content before filtering
    it.
   </P
><P
>    If you use a <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> version without zlib support, but want filtering to work on
    as much documents as possible, even those that would normally be sent compressed,
    you must use the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#PREVENT-COMPRESSION"
>prevent-compression</A
></TT
>
    action in conjunction with <TT
CLASS="LITERAL"
>filter</TT
>.
   </P
><P
>    Content filtering can achieve some of the same effects as the 
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>
    action, i.e. it can be used to block ads and banners. But the mechanism 
    works quite differently. One effective use, is to block ad banners 
    based on their size (see below), since many of these seem to be somewhat 
    standardized.
   </P
><P
>    <A
HREF="contact.html"
>Feedback</A
> with suggestions for new or
    improved filters is particularly welcome!
   </P
><P
>    The below list has only the names and a one-line description of each
    predefined filter. There are <A
HREF="filter-file.html#PREDEFINED-FILTERS"
>more
    verbose explanations</A
> of what these filters do in the <A
HREF="filter-file.html"
>filter file chapter</A
>.
   </P
></DD
><DT
>Example usage (with filters from the distribution <TT
CLASS="FILENAME"
>default.filter</TT
> file).
  See <A
HREF="filter-file.html#PREDEFINED-FILTERS"
>the Predefined Filters section</A
> for 
  more explanation on each:</DT
><DD
><P
>    <A
NAME="FILTER-JS-ANNOYANCES"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{js-annoyances}       # Get rid of particularly annoying JavaScript abuse.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-JS-EVENTS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{js-events}           # Kill all JS event bindings and timers (Radically destructive! Only for extra nasty sites).</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-HTML-ANNOYANCES"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{html-annoyances}     # Get rid of particularly annoying HTML abuse.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-CONTENT-COOKIES"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{content-cookies}     # Kill cookies that come in the HTML or JS content.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-REFRESH-TAGS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{refresh-tags}        # Kill automatic refresh tags (for dial-on-demand setups).</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-UNSOLICITED-POPUPS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{unsolicited-popups}  # Disable only unsolicited pop-up windows. Useful if your browser lacks this ability.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-ALL-POPUPS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{all-popups}          # Kill all popups in JavaScript and HTML. Useful if your browser lacks this ability.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-IMG-REORDER"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{img-reorder}         # Reorder attributes in &#60;img&#62; tags to make the banners-by-* filters more effective.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-BANNERS-BY-SIZE"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{banners-by-size}     # Kill banners by size.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-BANNERS-BY-LINK"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{banners-by-link}     # Kill banners by their links to known clicktrackers.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-WEBBUGS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{webbugs}             # Squish WebBugs (1x1 invisible GIFs used for user tracking).</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-TINY-TEXTFORMS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{tiny-textforms}      # Extend those tiny textareas up to 40x80 and kill the hard wrap.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-JUMPING-WINDOWS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{jumping-windows}     # Prevent windows from resizing and moving themselves.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-FRAMESET-BORDERS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{frameset-borders}    # Give frames a border and make them resizable.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-DEMORONIZER"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{demoronizer}         # Fix MS's non-standard use of standard charsets.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-SHOCKWAVE-FLASH"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{shockwave-flash}     # Kill embedded Shockwave Flash objects.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-QUICKTIME-KIOSKMODE"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{quicktime-kioskmode} # Make Quicktime movies saveable.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-FUN"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{fun}                 # Text replacements for subversive browsing fun!</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-CRUDE-PARENTAL"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{crude-parental}      # Crude parental filtering. Note that this filter doesn't work reliably.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-IE-EXPLOITS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{ie-exploits}         # Disable some known Internet Explorer bug exploits.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-SITE-SPECIFICS"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{site-specifics}      # Cure for site-specific problems. Don't apply generally!</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-NO-PING"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{no-ping}             # Removes non-standard ping attributes in &#60;a&#62; and &#60;area&#62; tags.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-GOOGLE"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{google}              # CSS-based block for Google text ads. Also removes a width limitation and the toolbar advertisement.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-YAHOO"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{yahoo}               # CSS-based block for Yahoo text ads. Also removes a width limitation.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-MSN"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{msn}                 # CSS-based block for MSN text ads. Also removes tracking URLs and a width limitation.</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    <A
NAME="FILTER-BLOGSPOT"
></A
>
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+filter{blogspot}            # Cleans up some Blogspot blogs. Read the fine print before using this.</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="FORCE-TEXT-MODE"
>8.5.16. force-text-mode</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Force <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> to treat a document as if it was in some kind of <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>text</I
></SPAN
> format.   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Declares a document as text, even if the <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> isn't detected as such.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    As explained <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER"
>above</A
></TT
>,
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> tries to only filter files that are
    in some kind of text format. The same restrictions apply to
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CONTENT-TYPE-OVERWRITE"
>content-type-overwrite</A
></TT
>.
    <TT
CLASS="LITERAL"
>force-text-mode</TT
> declares a document as text,
    without looking at the <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> first.
   </P
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>     Think twice before activating this action. Filtering binary data
     with regular expressions can cause file damage.
    </P
></TD
></TR
></TABLE
></DIV
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+force-text-mode
     </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="FORWARD-OVERRIDE"
>8.5.17. forward-override</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Change the forwarding settings based on User-Agent or request origin</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Overrules the forward directives in the configuration file.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Multi-value.</P
></DD
><DT
>Parameter:</DT
><DD
><P
></P
><UL
><LI
><P
><SPAN
CLASS="QUOTE"
>"forward ."</SPAN
> to use a direct connection without any additional proxies.</P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"forward 127.0.0.1:8123"</SPAN
> to use the HTTP proxy listening at 127.0.0.1 port 8123.
     </P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"forward-socks4a 127.0.0.1:9050 ."</SPAN
> to use the socks4a proxy listening at
      127.0.0.1 port 9050. Replace <SPAN
CLASS="QUOTE"
>"forward-socks4a"</SPAN
> with <SPAN
CLASS="QUOTE"
>"forward-socks4"</SPAN
>
      to use a socks4 connection  (with local DNS resolution) instead, use <SPAN
CLASS="QUOTE"
>"forward-socks5"</SPAN
>
      for socks5 connections (with remote DNS resolution).
     </P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"forward-socks4a 127.0.0.1:9050 proxy.example.org:8000"</SPAN
> to use the socks4a proxy
      listening at 127.0.0.1 port 9050 to reach the HTTP proxy listening at proxy.example.org port 8000.
      Replace <SPAN
CLASS="QUOTE"
>"forward-socks4a"</SPAN
> with <SPAN
CLASS="QUOTE"
>"forward-socks4"</SPAN
> to use a socks4 connection
      (with local DNS resolution) instead, use <SPAN
CLASS="QUOTE"
>"forward-socks5"</SPAN
>
      for socks5 connections (with remote DNS resolution).
     </P
></LI
></UL
></DD
><DT
>Notes:</DT
><DD
><P
>    This action takes parameters similar to the
    <A
HREF="config.html#FORWARDING"
>forward</A
> directives in the configuration
    file, but without the URL pattern. It can be used as replacement, but normally it's only
    used in cases where matching based on the request URL isn't sufficient.
   </P
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>     Please read the description for the <A
HREF="config.html#FORWARDING"
>forward</A
> directives before
     using this action. Forwarding to the wrong people will reduce your privacy and increase the
     chances of man-in-the-middle attacks.
    </P
><P
>     If the ports are missing or invalid, default values will be used. This might change
     in the future and you shouldn't rely on it. Otherwise incorrect syntax causes Privoxy
     to exit.
    </P
><P
>     Use the <A
HREF="http://config.privoxy.org/show-url-info"
TARGET="_top"
>show-url-info CGI page</A
>
     to verify that your forward settings do what you thought the do.
    </P
></TD
></TR
></TABLE
></DIV
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Always use direct connections for requests previously tagged as
# <SPAN
CLASS="QUOTE"
>"User-Agent: fetch libfetch/2.0"</SPAN
> and make sure
# resuming downloads continues to work.
# This way you can continue to use Tor for your normal browsing,
# without overloading the Tor network with your FreeBSD ports updates
# or downloads of bigger files like ISOs.
# Note that HTTP headers are easy to fake and therefore their
# values are as (un)trustworthy as your clients and users.
{+forward-override{forward .} \
 -hide-if-modified-since      \
 -overwrite-last-modified     \
}
TAG:^User-Agent: fetch libfetch/2\.0$
     </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HANDLE-AS-EMPTY-DOCUMENT"
>8.5.18. handle-as-empty-document</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Mark URLs that should be replaced by empty documents <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>if they get blocked</I
></SPAN
></P
></DD
><DT
>Effect:</DT
><DD
><P
>    This action alone doesn't do anything noticeable. It just marks URLs.
    If the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
> action <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>also applies</I
></SPAN
>,
    the presence or absence of this mark decides whether an HTML <SPAN
CLASS="QUOTE"
>"BLOCKED"</SPAN
>
    page, or an empty document will be sent to the client as a substitute for the blocked content.
    The <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>empty</I
></SPAN
> document isn't literally empty, but actually contains a single space.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Some browsers complain about syntax errors if JavaScript documents
    are blocked with <SPAN
CLASS="APPLICATION"
>Privoxy's</SPAN
>
    default HTML page; this option can be used to silence them.
    And of course this action can also be used to eliminate the <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
    BLOCKED message in frames.
   </P
><P
>    The content type for the empty document can be specified with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CONTENT-TYPE-OVERWRITE"
>content-type-overwrite{}</A
></TT
>,
    but usually this isn't necessary.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Block all documents on example.org that end with ".js",
# but send an empty document instead of the usual HTML message. 
{+block{Blocked JavaScript} +handle-as-empty-document}
example.org/.*\.js$
     </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HANDLE-AS-IMAGE"
>8.5.19. handle-as-image</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Mark URLs as belonging to images (so they'll be replaced by images <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>if they do get blocked</I
></SPAN
>, rather than HTML pages)</P
></DD
><DT
>Effect:</DT
><DD
><P
>    This action alone doesn't do anything noticeable. It just marks URLs as images.
    If the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
> action <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>also applies</I
></SPAN
>,
    the presence or absence of this mark decides whether an HTML <SPAN
CLASS="QUOTE"
>"blocked"</SPAN
>
    page, or a replacement image (as determined by the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker</A
></TT
> action) will be sent to the
    client as a substitute for the blocked content.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    The below generic example section is actually part of <TT
CLASS="FILENAME"
>default.action</TT
>.
    It marks all URLs with well-known image file name extensions as images and should
    be left intact. 
   </P
><P
>    Users will probably only want to use the handle-as-image action in conjunction with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>, to block sources of banners, whose URLs don't
    reflect the file type, like in the second example section.
   </P
><P
>    Note that you cannot treat HTML pages as images in most cases. For instance, (in-line) ad
    frames require an HTML page to be sent, or they won't display properly.
    Forcing <TT
CLASS="LITERAL"
>handle-as-image</TT
> in this situation will not replace the
    ad frame with an image, but lead to error messages.
   </P
></DD
><DT
>Example usage (sections):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Generic image extensions:
#
{+handle-as-image}
/.*\.(gif|jpg|jpeg|png|bmp|ico)$

# These don't look like images, but they're banners and should be
# blocked as images:
#
{+block{Nasty banners.} +handle-as-image}
nasty-banner-server.example.com/junk.cgi\?output=trash</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-ACCEPT-LANGUAGE"
>8.5.20. hide-accept-language</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Pretend to use different language settings.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes or replaces the <SPAN
CLASS="QUOTE"
>"Accept-Language:"</SPAN
> HTTP header in client requests.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Keyword: <SPAN
CLASS="QUOTE"
>"block"</SPAN
>, or any user defined value.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Faking the browser's language settings can be useful to make a
    foreign User-Agent set with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HIDE-USER-AGENT"
>hide-user-agent</A
></TT
>
    more believable.
   </P
><P
>    However some sites with content in different languages check the
    <SPAN
CLASS="QUOTE"
>"Accept-Language:"</SPAN
> to decide which one to take by default.
    Sometimes it isn't possible to later switch to another language without
    changing the <SPAN
CLASS="QUOTE"
>"Accept-Language:"</SPAN
> header first.
   </P
><P
>    Therefore it's a good idea to either only change the
    <SPAN
CLASS="QUOTE"
>"Accept-Language:"</SPAN
> header to languages you understand,
    or to languages that aren't wide spread.
   </P
><P
>    Before setting the <SPAN
CLASS="QUOTE"
>"Accept-Language:"</SPAN
> header
    to a rare language, you should consider that it helps to
    make your requests unique and thus easier to trace.
    If you don't plan to change this header frequently,
    you should stick to a common language. 
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Pretend to use Canadian language settings.
{+hide-accept-language{en-ca} \
+hide-user-agent{Mozilla/5.0 (X11; U; OpenBSD i386; en-CA; rv:1.8.0.4) Gecko/20060628 Firefox/1.5.0.4} \
}
/   </PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-CONTENT-DISPOSITION"
>8.5.21. hide-content-disposition</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Prevent download menus for content you prefer to view inside the browser.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes or replaces the <SPAN
CLASS="QUOTE"
>"Content-Disposition:"</SPAN
> HTTP header set by some servers.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Keyword: <SPAN
CLASS="QUOTE"
>"block"</SPAN
>, or any user defined value.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Some servers set the <SPAN
CLASS="QUOTE"
>"Content-Disposition:"</SPAN
> HTTP header for
    documents they assume you want to save locally before viewing them.
    The <SPAN
CLASS="QUOTE"
>"Content-Disposition:"</SPAN
> header contains the file name
    the browser is supposed to use by default.
   </P
><P
>    In most browsers that understand this header, it makes it impossible to
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>just view</I
></SPAN
> the document, without downloading it first,
    even if it's just a simple text file or an image.
   </P
><P
>    Removing the <SPAN
CLASS="QUOTE"
>"Content-Disposition:"</SPAN
> header helps
    to prevent this annoyance, but some browsers additionally check the
    <SPAN
CLASS="QUOTE"
>"Content-Type:"</SPAN
> header, before they decide if they can
    display a document without saving it first. In these cases, you have
    to change this header as well, before the browser stops displaying
    download menus.
   </P
><P
>    It is also possible to change the server's file name suggestion
    to another one, but in most cases it isn't worth the time to set
    it up.
   </P
><P
>    This action will probably be removed in the future,
    use server-header filters instead.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Disarm the download link in Sourceforge's patch tracker
{ -filter \
 +content-type-overwrite{text/plain}\
 +hide-content-disposition{block} }
 .sourceforge.net/tracker/download\.php</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-IF-MODIFIED-SINCE"
>8.5.22. hide-if-modified-since</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Prevent yet another way to track the user's steps between sessions.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"If-Modified-Since:"</SPAN
> HTTP client header or modifies its value. 
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Keyword: <SPAN
CLASS="QUOTE"
>"block"</SPAN
>, or a user defined value that specifies a range of hours.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Removing this header is useful for filter testing, where you want to force a real
    reload instead of getting status code <SPAN
CLASS="QUOTE"
>"304"</SPAN
>, which would cause the
    browser to use a cached copy of the page.
   </P
><P
>    Instead of removing the header, <TT
CLASS="LITERAL"
>hide-if-modified-since</TT
> can
    also add or subtract a random amount of time to/from the header's value.
    You specify a range of minutes where the random factor should be chosen from and
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> does the rest. A negative value means
    subtracting, a positive value adding.
   </P
><P
>    Randomizing the value of the <SPAN
CLASS="QUOTE"
>"If-Modified-Since:"</SPAN
> makes
    it less likely that the server can use the time as a cookie replacement,
    but you will run into caching problems if the random range is too high.
   </P
><P
>    It is a good idea to only use a small negative value and let
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#OVERWRITE-LAST-MODIFIED"
>overwrite-last-modified</A
></TT
>
    handle the greater changes.
   </P
><P
>    It is also recommended to use this action together with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-IF-NONE-MATCH"
>crunch-if-none-match</A
></TT
>,
    otherwise it's more or less pointless.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Let the browser revalidate but make tracking based on the time less likely.
{+hide-if-modified-since{-60} \
 +overwrite-last-modified{randomize} \
 +crunch-if-none-match}
/</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-FROM-HEADER"
>8.5.23. hide-from-header</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Keep your (old and ill) browser from telling web servers your email address</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes any existing <SPAN
CLASS="QUOTE"
>"From:"</SPAN
> HTTP header, or replaces it with the
    specified string.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Keyword: <SPAN
CLASS="QUOTE"
>"block"</SPAN
>, or any user defined value.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    The keyword <SPAN
CLASS="QUOTE"
>"block"</SPAN
> will completely remove the header 
    (not to be confused with the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>
    action).
   </P
><P
>    Alternately, you can specify any value you prefer to be sent to the web
    server. If you do, it is a matter of fairness not to use any address that
    is actually used by a real person.
   </P
><P
>    This action is rarely needed, as modern web browsers don't send
    <SPAN
CLASS="QUOTE"
>"From:"</SPAN
> headers anymore.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+hide-from-header{block}</PRE
></TD
></TR
></TABLE
> or
    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+hide-from-header{spam-me-senseless@sittingduck.example.com}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-REFERRER"
>8.5.24. hide-referrer</A
></H4
><A
NAME="HIDE-REFERER"
></A
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Conceal which link you followed to get to a particular site</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"Referer:"</SPAN
> (sic) HTTP header from the client request,
    or replaces it with a forged one.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
></P
><UL
><LI
><P
><SPAN
CLASS="QUOTE"
>"conditional-block"</SPAN
> to delete the header completely if the host has changed.</P
></LI
><LI
><P
><SPAN
CLASS="QUOTE"
>"conditional-forge"</SPAN
> to forge the header if the host has changed.</P
></LI
><LI
><P
><SPAN
CLASS="QUOTE"
>"block"</SPAN
> to delete the header unconditionally.</P
></LI
><LI
><P
><SPAN
CLASS="QUOTE"
>"forge"</SPAN
> to pretend to be coming from the homepage of the server we are talking to.</P
></LI
><LI
><P
>Any other string to set a user defined referrer.</P
></LI
></UL
></DD
><DT
>Notes:</DT
><DD
><P
>    <TT
CLASS="LITERAL"
>conditional-block</TT
> is the only parameter,
    that isn't easily detected in the server's log file. If it blocks the
    referrer, the request will look like the visitor used a bookmark or
    typed in the address directly.
   </P
><P
>    Leaving the referrer unmodified for requests on the same host
    allows the server owner to see the visitor's <SPAN
CLASS="QUOTE"
>"click path"</SPAN
>,
    but in most cases she could also get that information by comparing
    other parts of the log file: for example the User-Agent if it isn't
    a very common one, or the user's IP address if it doesn't change between
    different requests.
   </P
><P
>    Always blocking the referrer, or using a custom one, can lead to
    failures on servers that check the referrer before they answer any
    requests, in an attempt to prevent their content from being
    embedded or linked to elsewhere.
   </P
><P
>    Both <TT
CLASS="LITERAL"
>conditional-block</TT
> and <TT
CLASS="LITERAL"
>forge</TT
>
    will work with referrer checks, as long as content and valid referring page
    are on the same host. Most of the time that's the case.
   </P
><P
>  
    <TT
CLASS="LITERAL"
>hide-referer</TT
> is an alternate spelling of
    <TT
CLASS="LITERAL"
>hide-referrer</TT
> and the two can be can be freely
    substituted with each other. (<SPAN
CLASS="QUOTE"
>"referrer"</SPAN
> is the
    correct English spelling, however the HTTP specification has a bug - it
    requires it to be spelled as <SPAN
CLASS="QUOTE"
>"referer"</SPAN
>.) 
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+hide-referrer{forge}</PRE
></TD
></TR
></TABLE
> or
     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+hide-referrer{http://www.yahoo.com/}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="HIDE-USER-AGENT"
>8.5.25. hide-user-agent</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Try to conceal your type of browser and client operating system</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Replaces the value of the <SPAN
CLASS="QUOTE"
>"User-Agent:"</SPAN
> HTTP header
    in client requests with the specified value.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    Any user-defined string.
   </P
></DD
><DT
>Notes:</DT
><DD
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>     This can lead to problems on web sites that depend on looking at this header in
     order to customize their content for different browsers (which, by the
     way, is <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>NOT</I
></SPAN
> the right thing to do: good web sites
     work browser-independently). 
    </P
></TD
></TR
></TABLE
></DIV
><P
>    Using this action in multi-user setups or wherever different types of
    browsers will access the same <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> is
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not recommended</I
></SPAN
>. In single-user, single-browser
    setups, you might use it to delete your OS version information from
    the headers, because it is an invitation to exploit known bugs for your
    OS. It is also occasionally useful to forge this in order to access 
    sites that won't let you in otherwise (though there may be a good 
    reason in some cases). Example of this: some MSN sites will not 
    let <SPAN
CLASS="APPLICATION"
>Mozilla</SPAN
> enter, yet forging to a 
    <SPAN
CLASS="APPLICATION"
>Netscape 6.1</SPAN
> user-agent works just fine.
    (Must be just a silly MS goof, I'm sure :-).
   </P
><P
>     More information on known user-agent strings can be found at 
     <A
HREF="http://www.user-agents.org/"
TARGET="_top"
>http://www.user-agents.org/</A
>
     and 
     <A
HREF="http://en.wikipedia.org/wiki/User_agent"
TARGET="_top"
>http://en.wikipedia.org/wiki/User_agent</A
>.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+hide-user-agent{Netscape 6.1 (X11; I; Linux 2.4.18 i686)}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="LIMIT-CONNECT"
>8.5.26. limit-connect</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Prevent abuse of <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> as a TCP proxy relay or disable SSL for untrusted sites</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Specifies to which ports HTTP CONNECT requests are allowable.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    A comma-separated list of ports or port ranges (the latter using dashes, with the minimum
    defaulting to 0 and the maximum to 65K).
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    By default, i.e. if no <TT
CLASS="LITERAL"
>limit-connect</TT
> action applies,
    <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> allows HTTP CONNECT requests to all
    ports. Use <TT
CLASS="LITERAL"
>limit-connect</TT
> if fine-grained control
    is desired for some or all destinations.
   </P
><P
>    The CONNECT methods exists in HTTP to allow access to secure websites
    (<SPAN
CLASS="QUOTE"
>"https://"</SPAN
> URLs) through proxies. It works very simply:
    the proxy connects to the server on the specified port, and then
    short-circuits its connections to the client and to the remote server.
    This means CONNECT-enabled proxies can be used as TCP relays very easily.
  </P
><P
>   <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> relays HTTPS traffic without seeing
   the decoded content. Websites can leverage this limitation to circumvent <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>'s
   filters. By specifying an invalid port range you can disable HTTPS entirely.
  </P
></DD
><DT
>Example usages:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+limit-connect{443}                   # Port 443 is OK.
+limit-connect{80,443}                # Ports 80 and 443 are OK.
+limit-connect{-3, 7, 20-100, 500-}   # Ports less than 3, 7, 20 to 100 and above 500 are OK.
+limit-connect{-}                     # All ports are OK
+limit-connect{,}                     # No HTTPS/SSL traffic is allowed</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="PREVENT-COMPRESSION"
>8.5.27. prevent-compression</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>    Ensure that servers send the content uncompressed, so it can be
    passed through <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER"
>filter</A
></TT
>s.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Removes the Accept-Encoding header which can be used to ask for compressed transfer.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    More and more websites send their content compressed by default, which
    is generally a good idea and saves bandwidth. But the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER"
>filter</A
></TT
> and
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#DEANIMATE-GIFS"
>deanimate-gifs</A
></TT
>
    actions need access to the uncompressed data.
   </P
><P
>    When compiled with zlib support (available since <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> 3.0.7), content that should be
    filtered is decompressed on-the-fly and you don't have to worry about this action.
    If you are using an older <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> version, or one that hasn't been compiled with zlib
    support, this action can be used to convince the server to send the content uncompressed.
   </P
><P
>    Most text-based instances compress very well, the size is seldom decreased by less than 50%,
    for markup-heavy instances like news feeds saving more than 90% of the original size isn't
    unusual. 
   </P
><P
>    Not using compression will therefore slow down the transfer, and you should only
    enable this action if you really need it. As of <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> 3.0.7 it's disabled in all
    predefined action settings.
   </P
><P
>    Note that some (rare) ill-configured sites don't handle requests for uncompressed
    documents correctly. Broken PHP applications tend to send an empty document body,
    some IIS versions only send the beginning of the content. If you enable
    <TT
CLASS="LITERAL"
>prevent-compression</TT
> per default, you might want to add
    exceptions for those sites. See the example for how to do that.
   </P
></DD
><DT
>Example usage (sections):</DT
><DD
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Selectively turn off compression, and enable a filter
#
{ +filter{tiny-textforms} +prevent-compression }
# Match only these sites
 .google.
 sourceforge.net
 sf.net

# Or instead, we could set a universal default:
#
{ +prevent-compression }
 / # Match all sites

# Then maybe make exceptions for broken sites:
#
{ -prevent-compression }
.compusa.com/</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="OVERWRITE-LAST-MODIFIED"
>8.5.28. overwrite-last-modified</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Prevent yet another way to track the user's steps between sessions.</P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
> HTTP server header or modifies its value. 
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    One of the keywords: <SPAN
CLASS="QUOTE"
>"block"</SPAN
>, <SPAN
CLASS="QUOTE"
>"reset-to-request-time"</SPAN
>
    and <SPAN
CLASS="QUOTE"
>"randomize"</SPAN
>
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Removing the <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
> header is useful for filter
    testing, where you want to force a real reload instead of getting status
    code <SPAN
CLASS="QUOTE"
>"304"</SPAN
>, which would cause the browser to reuse the old
    version of the page.
   </P
><P
>    The <SPAN
CLASS="QUOTE"
>"randomize"</SPAN
> option overwrites the value of the
    <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
> header with a randomly chosen time
    between the original value and the current time. In theory the server
    could send each document with a different <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
>
    header to track visits without using cookies. <SPAN
CLASS="QUOTE"
>"Randomize"</SPAN
>
    makes it impossible and the browser can still revalidate cached documents. 
   </P
><P
>    <SPAN
CLASS="QUOTE"
>"reset-to-request-time"</SPAN
> overwrites the value of the
    <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
> header with the current time. You could use
    this option together with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HIDE-IF-MODIFIED-SINCE"
>hide-if-modified-since</A
></TT
>
    to further customize your random range.
   </P
><P
>    The preferred parameter here is <SPAN
CLASS="QUOTE"
>"randomize"</SPAN
>. It is safe
    to use, as long as the time settings are more or less correct.
    If the server sets the <SPAN
CLASS="QUOTE"
>"Last-Modified:"</SPAN
> header to the time
    of the request, the random range becomes zero and the value stays the same.
    Therefore you should later randomize it a second time with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HIDE-IF-MODIFIED-SINCE"
>hided-if-modified-since</A
></TT
>,
    just to be sure. 
   </P
><P
>    It is also recommended to use this action together with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-IF-NONE-MATCH"
>crunch-if-none-match</A
></TT
>.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Let the browser revalidate without being tracked across sessions
{ +hide-if-modified-since{-60} \
 +overwrite-last-modified{randomize} \
 +crunch-if-none-match}
/</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="REDIRECT"
>8.5.29. redirect</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>    Redirect requests to other sites.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Convinces the browser that the requested document has been moved
    to another location and the browser should get it from there.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    An absolute URL or a single pcrs command.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Requests to which this action applies are answered with a
    HTTP redirect to URLs of your choosing. The new URL is
    either provided as parameter, or derived by applying a
    single pcrs command to the original URL.
   </P
><P
>    This action will be ignored if you use it together with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>.
    It can be combined with
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FAST-REDIRECTS"
>fast-redirects{check-decoded-url}</A
></TT
>
    to redirect to a decoded version of a rewritten URL.
   </P
><P
>    Use this action carefully, make sure not to create redirection loops
    and be aware that using your own redirects might make it
    possible to fingerprint your requests.
   </P
><P
>    In case of problems with your redirects, or simply to watch
    them working, enable <A
HREF="config.html#DEBUG"
>debug 128</A
>.
   </P
></DD
><DT
>Example usages:</DT
><DD
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Replace example.com's style sheet with another one
{ +redirect{http://localhost/css-replacements/example.com.css} }
 example.com/stylesheet\.css

# Create a short, easy to remember nickname for a favorite site
# (relies on the browser accept and forward invalid URLs to <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>)
{ +redirect{http://www.privoxy.org/user-manual/actions-file.html} }
 a

# Always use the expanded view for Undeadly.org articles
# (Note the $ at the end of the URL pattern to make sure
# the request for the rewritten URL isn't redirected as well)
{+redirect{s@$@&#38;mode=expanded@}}
undeadly.org/cgi\?action=article&#38;sid=\d*$

# Redirect Google search requests to MSN
{+redirect{s@^http://[^/]*/search\?q=([^&#38;]*).*@http://search.msn.com/results.aspx?q=$1@}}
.google.com/search

# Redirect MSN search requests to Yahoo
{+redirect{s@^http://[^/]*/results\.aspx\?q=([^&#38;]*).*@http://search.yahoo.com/search?p=$1@}}
search.msn.com//results\.aspx\?q=

# Redirect remote requests for this manual
# to the local version delivered by Privoxy
{+redirect{s@^http://www@http://config@}}
www.privoxy.org/user-manual/</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="SERVER-HEADER-FILTER"
>8.5.30. server-header-filter</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>   Rewrite or remove single server headers.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    All server headers to which this action applies are filtered on-the-fly
    through the specified regular expression based substitutions.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    The name of a server-header filter, as defined in one of the
    <A
HREF="filter-file.html"
>filter files</A
>.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Server-header filters are applied to each header on its own, not to
    all at once. This makes it easier to diagnose problems, but on the downside
    you can't write filters that only change header x if header y's value is z.
    You can do that by using tags though.
   </P
><P
>    Server-header filters are executed after the other header actions have finished
    and use their output as input.
   </P
><P
>    Please refer to the <A
HREF="filter-file.html"
>filter file chapter</A
>
    to learn which server-header filters are available by default, and how to
    create your own.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{+server-header-filter{html-to-xml}}
example.org/xml-instance-that-is-delivered-as-html

{+server-header-filter{xml-to-html}}
example.org/instance-that-is-delivered-as-xml-but-is-not
    </PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="SERVER-HEADER-TAGGER"
>8.5.31. server-header-tagger</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>   Enable or disable filters based on the Content-Type header.
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Server headers to which this action applies are filtered on-the-fly through
    the specified regular expression based substitutions, the result is used as
    tag.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    The name of a server-header tagger, as defined in one of the
    <A
HREF="filter-file.html"
>filter files</A
>.
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    Server-header taggers are applied to each header on its own,
    and as the header isn't modified, each tagger <SPAN
CLASS="QUOTE"
>"sees"</SPAN
>
    the original.
   </P
><P
>    Server-header taggers are executed before all other header actions
    that modify server headers. Their tags can be used to control
    all of the other server-header actions, the content filters
    and the crunch actions (<A
HREF="actions-file.html#REDIRECT"
>redirect</A
>
    and <A
HREF="actions-file.html#BLOCK"
>block</A
>).
   </P
><P
>    Obviously crunching based on tags created by server-header taggers
    doesn't prevent the request from showing up in the server's log file.
   </P
></DD
><DT
>Example usage (section):</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Tag every request with the content type declared by the server
{+server-header-tagger{content-type}}
/
    </PRE
></TD
></TR
></TABLE
>
    </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="SESSION-COOKIES-ONLY"
>8.5.32. session-cookies-only</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>    Allow only temporary <SPAN
CLASS="QUOTE"
>"session"</SPAN
> cookies (for the current
    browser session <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>only</I
></SPAN
>). 
   </P
></DD
><DT
>Effect:</DT
><DD
><P
>    Deletes the <SPAN
CLASS="QUOTE"
>"expires"</SPAN
> field from <SPAN
CLASS="QUOTE"
>"Set-Cookie:"</SPAN
>
    server headers. Most browsers will not store such cookies permanently and
    forget them in between sessions.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Boolean.</P
></DD
><DT
>Parameter:</DT
><DD
><P
>    N/A
   </P
></DD
><DT
>Notes:</DT
><DD
><P
>    This is less strict than <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
></TT
> / 
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
></TT
> and allows you to browse
    websites that insist or rely on setting cookies, without compromising your privacy too badly.
   </P
><P
>    Most browsers will not permanently store cookies that have been processed by
    <TT
CLASS="LITERAL"
>session-cookies-only</TT
> and will forget about them between sessions.
    This makes profiling cookies useless, but won't break sites which require cookies so
    that you can log in for transactions. This is generally turned on for all 
    sites, and is the recommended setting.
   </P
><P
>    It makes <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>no sense at all</I
></SPAN
> to use <TT
CLASS="LITERAL"
>session-cookies-only</TT
>
    together with <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
></TT
> or
    <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
></TT
>. If you do, cookies
    will be plainly killed.
   </P
><P
>    Note that it is up to the browser how it handles such cookies without an <SPAN
CLASS="QUOTE"
>"expires"</SPAN
>
    field. If you use an exotic browser, you might want to try it out to be sure.
   </P
><P
>    This setting also has no effect on cookies that may have been stored
    previously by the browser before starting <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>.
    These would have to be removed manually.
   </P
><P
>     <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> also uses  
     the <A
HREF="actions-file.html#FILTER-CONTENT-COOKIES"
>content-cookies filter</A
> 
     to block some types of cookies. Content cookies are not effected by 
     <TT
CLASS="LITERAL"
>session-cookies-only</TT
>.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>     <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+session-cookies-only</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H4
CLASS="SECT3"
><A
NAME="SET-IMAGE-BLOCKER"
>8.5.33. set-image-blocker</A
></H4
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>Typical use:</DT
><DD
><P
>Choose the replacement for blocked images</P
></DD
><DT
>Effect:</DT
><DD
><P
>     This action alone doesn't do anything noticeable. If <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>both</I
></SPAN
>
     <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
> <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>and</I
></SPAN
> <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
></TT
> <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>also</I
></SPAN
>
     apply, i.e. if the request is to be blocked as an image,
     <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>then</I
></SPAN
> the parameter of this action decides what will be
     sent as a replacement.
   </P
></DD
><DT
>Type:</DT
><DD
><P
>Parameterized.</P
></DD
><DT
>Parameter:</DT
><DD
><P
></P
><UL
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"pattern"</SPAN
> to send a built-in checkerboard pattern image. The image is visually
      decent, scales very well, and makes it obvious where banners were busted.
     </P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"blank"</SPAN
> to send a built-in transparent image. This makes banners disappear
      completely, but makes it hard to detect where <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> has blocked
      images on a given page and complicates troubleshooting if <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
      has blocked innocent images, like navigation icons.
     </P
></LI
><LI
><P
>      <SPAN
CLASS="QUOTE"
>"<TT
CLASS="REPLACEABLE"
><I
>target-url</I
></TT
>"</SPAN
> to
      send a redirect to <TT
CLASS="REPLACEABLE"
><I
>target-url</I
></TT
>. You can redirect
      to any image anywhere, even in your local filesystem via <SPAN
CLASS="QUOTE"
>"file:///"</SPAN
> URL. 
      (But note that not all browsers support redirecting to a local file system).
     </P
><P
>      A good application of redirects is to use special <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>-built-in
      URLs, which send the built-in images, as <TT
CLASS="REPLACEABLE"
><I
>target-url</I
></TT
>.
      This has the same visual effect as specifying <SPAN
CLASS="QUOTE"
>"blank"</SPAN
> or <SPAN
CLASS="QUOTE"
>"pattern"</SPAN
> in
      the first place, but enables your browser to cache the replacement image, instead of requesting
      it over and over again.
     </P
></LI
></UL
></DD
><DT
>Notes:</DT
><DD
><P
>    The URLs for the built-in images are <SPAN
CLASS="QUOTE"
>"http://config.privoxy.org/send-banner?type=<TT
CLASS="REPLACEABLE"
><I
>type</I
></TT
>"</SPAN
>, where <TT
CLASS="REPLACEABLE"
><I
>type</I
></TT
> is
    either <SPAN
CLASS="QUOTE"
>"blank"</SPAN
> or <SPAN
CLASS="QUOTE"
>"pattern"</SPAN
>.
   </P
><P
>    There is a third (advanced) type, called <SPAN
CLASS="QUOTE"
>"auto"</SPAN
>. It is <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>NOT</I
></SPAN
> to be
    used in <TT
CLASS="LITERAL"
>set-image-blocker</TT
>, but meant for use from <A
HREF="filter-file.html"
>filters</A
>.
    Auto will select the type of image that would have applied to the referring page, had it been an image.
   </P
></DD
><DT
>Example usage:</DT
><DD
><P
>    Built-in pattern:
   </P
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+set-image-blocker{pattern}</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    Redirect to the BSD daemon:
   </P
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+set-image-blocker{http://www.freebsd.org/gifs/dae_up3.gif}</PRE
></TD
></TR
></TABLE
>
   </P
><P
>    Redirect to the built-in pattern for better caching:
   </P
><P
>    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="SCREEN"
>+set-image-blocker{http://config.privoxy.org/send-banner?type=pattern}</PRE
></TD
></TR
></TABLE
>
   </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN4263"
>8.5.34. Summary</A
></H3
><P
> Note that many of these actions have the potential to cause a page to
 misbehave, possibly even not to display at all. There are many ways 
 a site designer may choose to design his site, and what HTTP header 
 content, and other criteria, he may depend on. There is no way to have hard
 and fast rules for all sites. See the <A
HREF="appendix.html#ACTIONSANAT"
>Appendix</A
> for a brief example on troubleshooting
 actions.</P
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="ALIASES"
>8.6. Aliases</A
></H2
><P
> Custom <SPAN
CLASS="QUOTE"
>"actions"</SPAN
>, known to <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
 as <SPAN
CLASS="QUOTE"
>"aliases"</SPAN
>, can be defined by combining other actions.
 These can in turn be invoked just like the built-in actions.
 Currently, an alias name can contain any character except space, tab,
 <SPAN
CLASS="QUOTE"
>"="</SPAN
>,
 <SPAN
CLASS="QUOTE"
>"{"</SPAN
> and <SPAN
CLASS="QUOTE"
>"}"</SPAN
>, but we <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>strongly 
 recommend</I
></SPAN
> that you only use <SPAN
CLASS="QUOTE"
>"a"</SPAN
> to <SPAN
CLASS="QUOTE"
>"z"</SPAN
>,
 <SPAN
CLASS="QUOTE"
>"0"</SPAN
> to <SPAN
CLASS="QUOTE"
>"9"</SPAN
>, <SPAN
CLASS="QUOTE"
>"+"</SPAN
>, and <SPAN
CLASS="QUOTE"
>"-"</SPAN
>.
 Alias names are not case sensitive, and are not required to start with a
 <SPAN
CLASS="QUOTE"
>"+"</SPAN
> or <SPAN
CLASS="QUOTE"
>"-"</SPAN
> sign, since they are merely textually
 expanded.</P
><P
> Aliases can be used throughout the actions file, but they <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>must be
 defined in a special section at the top of the file!</I
></SPAN
>
 And there can only be one such section per actions file. Each actions file may
 have its own alias section, and the aliases defined in it are only visible
 within that file.</P
><P
> There are two main reasons to use aliases: One is to save typing for frequently
 used combinations of actions, the other one is a gain in flexibility: If you
 decide once how you want to handle shops by defining an alias called
 <SPAN
CLASS="QUOTE"
>"shop"</SPAN
>, you can later change your policy on shops in
 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>one</I
></SPAN
> place, and your changes will take effect everywhere
 in the actions file where the <SPAN
CLASS="QUOTE"
>"shop"</SPAN
> alias is used. Calling aliases
 by their purpose also makes your actions files more readable.</P
><P
> Currently, there is one big drawback to using aliases, though:
 <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>'s built-in web-based action file
 editor honors aliases when reading the actions files, but it expands
 them before writing. So the effects of your aliases are of course preserved,
 but the aliases themselves are lost when you edit sections that use aliases
 with it.</P
><P
> Now let's define some aliases...</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
> # Useful custom aliases we can use later.
 #
 # Note the (required!) section header line and that this section
 # must be at the top of the actions file!
 #
 {{alias}}

 # These aliases just save typing later:
 # (Note that some already use other aliases!)
 #
 +crunch-all-cookies = +<A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
> +<A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
>
 -crunch-all-cookies = -<A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
> -<A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
>
 +block-as-image      = +block{Blocked image.} +handle-as-image
 allow-all-cookies   = -crunch-all-cookies -<A
HREF="actions-file.html#SESSION-COOKIES-ONLY"
>session-cookies-only</A
> -<A
HREF="actions-file.html#FILTER-CONTENT-COOKIES"
>filter{content-cookies}</A
>

 # These aliases define combinations of actions
 # that are useful for certain types of sites:
 #
 fragile     = -<A
HREF="actions-file.html#BLOCK"
>block</A
> -<A
HREF="actions-file.html#FILTER"
>filter</A
> -crunch-all-cookies -<A
HREF="actions-file.html#FAST-REDIRECTS"
>fast-redirects</A
> -<A
HREF="actions-file.html#HIDE-REFERER"
>hide-referrer</A
> -<A
HREF="actions-file.html#PREVENT-COMPRESSION"
>prevent-compression</A
>

 shop        = -crunch-all-cookies -<A
HREF="actions-file.html#FILTER-ALL-POPUPS"
>filter{all-popups}</A
>

 # Short names for other aliases, for really lazy people ;-)
 #
 c0 = +crunch-all-cookies
 c1 = -crunch-all-cookies</PRE
></TD
></TR
></TABLE
></P
><P
> ...and put them to use. These sections would appear in the lower part of an 
 actions file and define exceptions to the default actions (as specified further
 up for the <SPAN
CLASS="QUOTE"
>"/"</SPAN
> pattern):</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
> # These sites are either very complex or very keen on
 # user data and require minimal interference to work:
 #
 {fragile}
 .office.microsoft.com
 .windowsupdate.microsoft.com
 # Gmail is really mail.google.com, not gmail.com
 mail.google.com

 # Shopping sites:
 # Allow cookies (for setting and retrieving your customer data)
 #           
 {shop}
 .quietpc.com
 .worldpay.com   # for quietpc.com
 mybank.example.com

 # These shops require pop-ups:
 #
 {-filter{all-popups} -filter{unsolicited-popups}}
  .dabs.com
  .overclockers.co.uk</PRE
></TD
></TR
></TABLE
></P
><P
> Aliases like <SPAN
CLASS="QUOTE"
>"shop"</SPAN
> and <SPAN
CLASS="QUOTE"
>"fragile"</SPAN
> are typically used for 
 <SPAN
CLASS="QUOTE"
>"problem"</SPAN
> sites that require more than one action to be disabled 
 in order to function properly.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="ACT-EXAMPLES"
>8.7. Actions Files Tutorial</A
></H2
><P
> The above chapters have shown <A
HREF="actions-file.html"
>which actions files
 there are and how they are organized</A
>, how actions are <A
HREF="actions-file.html#ACTIONS"
>specified</A
> and <A
HREF="actions-file.html#ACTIONS-APPLY"
>applied
 to URLs</A
>, how <A
HREF="actions-file.html#AF-PATTERNS"
>patterns</A
> work, and how to
 define and use <A
HREF="actions-file.html#ALIASES"
>aliases</A
>. Now, let's look at an
 example <TT
CLASS="FILENAME"
>match-all.action</TT
>, <TT
CLASS="FILENAME"
>default.action</TT
>
 and <TT
CLASS="FILENAME"
>user.action</TT
> file and see how all these pieces come together:</P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN4327"
>8.7.1. match-all.action</A
></H3
><P
> Remember <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all actions are disabled when matching starts</I
></SPAN
>,
 so we have to explicitly enable the ones we want.</P
><P
> While the <TT
CLASS="FILENAME"
>match-all.action</TT
> file only contains a
 single section, it is probably the most important one. It has only one
 pattern, <SPAN
CLASS="QUOTE"
>"<TT
CLASS="LITERAL"
>/</TT
>"</SPAN
>, but this pattern
 <A
HREF="actions-file.html#AF-PATTERNS"
>matches all URLs</A
>. Therefore, the set of
 actions used in this <SPAN
CLASS="QUOTE"
>"default"</SPAN
> section <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>will
 be applied to all requests as a start</I
></SPAN
>. It can  be partly or
 wholly overridden by other actions files like <TT
CLASS="FILENAME"
>default.action</TT
>
 and <TT
CLASS="FILENAME"
>user.action</TT
>, but it will still be largely responsible
 for your overall browsing experience.</P
><P
> Again, at the start of matching, all actions are disabled, so there is
 no need to disable any actions here. (Remember: a <SPAN
CLASS="QUOTE"
>"+"</SPAN
>
 preceding the action name enables the action, a <SPAN
CLASS="QUOTE"
>"-"</SPAN
> disables!).
 Also note how this long line has been made more readable by splitting it into
 multiple lines with line continuation.</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ \
 +<A
HREF="actions-file.html#CHANGE-X-FORWARDED-FOR"
>change-x-forwarded-for{block}</A
> \
 +<A
HREF="actions-file.html#HIDE-FROM-HEADER"
>hide-from-header{block}</A
> \
 +<A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker{pattern}</A
> \
}
/ # Match all URLs
 </PRE
></TD
></TR
></TABLE
></P
><P
> The default behavior is now set.</P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN4349"
>8.7.2. default.action</A
></H3
><P
> If you aren't a developer, there's no need for you to edit the
 <TT
CLASS="FILENAME"
>default.action</TT
> file. It is maintained by
 the <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> developers and if you disagree with some of the
 sections, you should overrule them in your <TT
CLASS="FILENAME"
>user.action</TT
>.</P
><P
> Understanding the <TT
CLASS="FILENAME"
>default.action</TT
> file can
 help you with your <TT
CLASS="FILENAME"
>user.action</TT
>, though.</P
><P
> The first section in this file is a special section for internal use
 that prevents older <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> versions from reading the file:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Settings -- Don't change! For internal Privoxy use ONLY.
##########################################################################
{{settings}}
for-privoxy-version=3.0.11</PRE
></TD
></TR
></TABLE
></P
><P
> After that comes the (optional) alias section. We'll use the example
 section from the above <A
HREF="actions-file.html#ALIASES"
>chapter on aliases</A
>,
 that also explains why and how aliases are used:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Aliases
##########################################################################
{{alias}}

 # These aliases just save typing later:
 # (Note that some already use other aliases!)
 #
 +crunch-all-cookies = +<A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
> +<A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
>
 -crunch-all-cookies = -<A
HREF="actions-file.html#CRUNCH-INCOMING-COOKIES"
>crunch-incoming-cookies</A
> -<A
HREF="actions-file.html#CRUNCH-OUTGOING-COOKIES"
>crunch-outgoing-cookies</A
>
 +block-as-image      = +block{Blocked image.} +handle-as-image
 mercy-for-cookies   = -crunch-all-cookies -<A
HREF="actions-file.html#SESSION-COOKIES-ONLY"
>session-cookies-only</A
> -<A
HREF="actions-file.html#FILTER-CONTENT-COOKIES"
>filter{content-cookies}</A
>

 # These aliases define combinations of actions
 # that are useful for certain types of sites:
 #
 fragile     = -<A
HREF="actions-file.html#BLOCK"
>block</A
> -<A
HREF="actions-file.html#FILTER"
>filter</A
> -crunch-all-cookies -<A
HREF="actions-file.html#FAST-REDIRECTS"
>fast-redirects</A
> -<A
HREF="actions-file.html#HIDE-REFERER"
>hide-referrer</A
>
 shop        = -crunch-all-cookies -<A
HREF="actions-file.html#FILTER-ALL-POPUPS"
>filter{all-popups}</A
></PRE
></TD
></TR
></TABLE
></P
><P
> The first of our specialized sections is concerned with <SPAN
CLASS="QUOTE"
>"fragile"</SPAN
>
 sites, i.e. sites that require minimum interference, because they are either
 very complex or very keen on tracking you (and have mechanisms in place that
 make them unusable for people who avoid being tracked). We will simply use
 our pre-defined <TT
CLASS="LITERAL"
>fragile</TT
> alias instead of stating the list
 of actions explicitly:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Exceptions for sites that'll break under the default action set:
##########################################################################

# "Fragile" Use a minimum set of actions for these sites (see alias above):
#
{ fragile }
.office.microsoft.com           # surprise, surprise!
.windowsupdate.microsoft.com
mail.google.com</PRE
></TD
></TR
></TABLE
></P
><P
> Shopping sites are not as fragile, but they typically
 require cookies to log in, and pop-up windows for shopping
 carts or item details. Again, we'll use a pre-defined alias:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Shopping sites:
#
{ shop }
.quietpc.com 
.worldpay.com   # for quietpc.com
.jungle.com
.scan.co.uk</PRE
></TD
></TR
></TABLE
></P
><P
> The <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FAST-REDIRECTS"
>fast-redirects</A
></TT
>
 action, which may have been enabled in <TT
CLASS="FILENAME"
>match-all.action</TT
>,
 breaks some sites. So disable it for popular sites where we know it misbehaves:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ -<A
HREF="actions-file.html#FAST-REDIRECTS"
>fast-redirects</A
> }
login.yahoo.com
edit.*.yahoo.com
.google.com
.altavista.com/.*(like|url|link):http
.altavista.com/trans.*urltext=http
.nytimes.com</PRE
></TD
></TR
></TABLE
></P
><P
> It is important that <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> knows which
 URLs belong to images, so that <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>if</I
></SPAN
> they are to
 be blocked, a substitute image can be sent, rather than an HTML page.
 Contacting the remote site to find out is not an option, since it
 would destroy the loading time advantage of banner blocking, and it
 would feed the advertisers information about you. We can mark any
 URL as an image with the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
></TT
> action,
 and marking all URLs that end in a known image file extension is a
 good start:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Images:
##########################################################################

# Define which file types will be treated as images, in case they get
# blocked further down this file:
#
{ +<A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
> }
/.*\.(gif|jpe?g|png|bmp|ico)$</PRE
></TD
></TR
></TABLE
></P
><P
> And then there are known banner sources. They often use scripts to
 generate the banners, so it won't be visible from the URL that the
 request is for an image. Hence we block them <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>and</I
></SPAN
>
 mark them as images in one go, with the help of our
 <TT
CLASS="LITERAL"
>+block-as-image</TT
> alias defined above. (We could of
 course just as well use <TT
CLASS="LITERAL"
>+<A
HREF="actions-file.html#BLOCK"
>block</A
>
 +<A
HREF="actions-file.html#HANDLE-AS-IMAGE"
>handle-as-image</A
></TT
> here.)
 Remember that the type of the replacement image is chosen by the
 <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker</A
></TT
>
 action. Since all URLs have matched the default section with its
 <TT
CLASS="LITERAL"
>+<A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker</A
>{pattern}</TT
>
 action before, it still applies and needn't be repeated:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Known ad generators:
#
{ +block-as-image }
ar.atwola.com 
.ad.doubleclick.net
.ad.*.doubleclick.net
.a.yimg.com/(?:(?!/i/).)*$
.a[0-9].yimg.com/(?:(?!/i/).)*$
bs*.gsanet.com
.qkimg.net</PRE
></TD
></TR
></TABLE
></P
><P
> One of the most important jobs of <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
 is to block banners. Many of these can be <SPAN
CLASS="QUOTE"
>"blocked"</SPAN
>
 by the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#FILTER"
>filter</A
>{banners-by-size}</TT
>
 action, which we enabled above, and which deletes the references to banner
 images from the pages while they are loaded, so the browser doesn't request
 them anymore, and hence they don't need to be blocked here. But this naturally
 doesn't catch all banners, and some people choose not to use filters, so we
 need a comprehensive list of patterns for banner URLs here, and apply the
 <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
> action to them.</P
><P
> First comes many generic patterns, which do most of the work, by
 matching typical domain and path name components of banners. Then comes
 a list of individual patterns for specific sites, which is omitted here
 to keep the example short:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Block these fine banners:
##########################################################################
{ <A
HREF="actions-file.html#BLOCK"
>+block{Banner ads.}</A
> }

# Generic patterns:
# 
ad*.
.*ads.
banner?.
count*.
/.*count(er)?\.(pl|cgi|exe|dll|asp|php[34]?)
/(?:.*/)?(publicite|werbung|rekla(ma|me|am)|annonse|maino(kset|nta|s)?)/

# Site-specific patterns (abbreviated):
#
.hitbox.com</PRE
></TD
></TR
></TABLE
></P
><P
> It's quite remarkable how many advertisers actually call their banner
 servers ads.<TT
CLASS="REPLACEABLE"
><I
>company</I
></TT
>.com, or call the directory
 in which the banners are stored simply <SPAN
CLASS="QUOTE"
>"banners"</SPAN
>. So the above
 generic patterns are surprisingly effective.</P
><P
> But being very generic, they necessarily also catch URLs that we don't want
 to block. The pattern <TT
CLASS="LITERAL"
>.*ads.</TT
> e.g. catches 
 <SPAN
CLASS="QUOTE"
>"nasty-<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>ads</I
></SPAN
>.nasty-corp.com"</SPAN
> as intended,
 but also <SPAN
CLASS="QUOTE"
>"downlo<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>ads</I
></SPAN
>.sourcefroge.net"</SPAN
> or
 <SPAN
CLASS="QUOTE"
>"<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>ads</I
></SPAN
>l.some-provider.net."</SPAN
> So here come some
 well-known exceptions to the <TT
CLASS="LITERAL"
>+<A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>
 section above.</P
><P
> Note that these are exceptions to exceptions from the default! Consider the URL
 <SPAN
CLASS="QUOTE"
>"downloads.sourcefroge.net"</SPAN
>: Initially, all actions are deactivated,
 so it wouldn't get blocked. Then comes the defaults section, which matches the
 URL, but just deactivates the <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>
 action once again. Then it matches <TT
CLASS="LITERAL"
>.*ads.</TT
>, an exception to the
 general non-blocking policy, and suddenly
 <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>+block</A
></TT
> applies. And now, it'll match
 <TT
CLASS="LITERAL"
>.*loads.</TT
>, where <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>-block</A
></TT
>
 applies, so (unless it matches <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>again</I
></SPAN
> further down) it ends up
 with no <TT
CLASS="LITERAL"
><A
HREF="actions-file.html#BLOCK"
>block</A
></TT
> action applying.</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>##########################################################################
# Save some innocent victims of the above generic block patterns:
##########################################################################

# By domain:
# 
{ -<A
HREF="actions-file.html#BLOCK"
>block</A
> }
adv[io]*.  # (for advogato.org and advice.*)
adsl.      # (has nothing to do with ads)
adobe.     # (has nothing to do with ads either)
ad[ud]*.   # (adult.* and add.*)
.edu       # (universities don't host banners (yet!))
.*loads.   # (downloads, uploads etc)

# By path:
#
/.*loads/

# Site-specific:
#
www.globalintersec.com/adv # (adv = advanced)
www.ugu.com/sui/ugu/adv</PRE
></TD
></TR
></TABLE
></P
><P
> Filtering source code can have nasty side effects,
 so make an exception for our friends at sourceforge.net,
 and all paths with <SPAN
CLASS="QUOTE"
>"cvs"</SPAN
> in them. Note that
 <TT
CLASS="LITERAL"
>-<A
HREF="actions-file.html#FILTER"
>filter</A
></TT
>
 disables <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>all</I
></SPAN
> filters in one fell swoop!</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Don't filter code!
#
{ -<A
HREF="actions-file.html#FILTER"
>filter</A
> }
/(.*/)?cvs
bugzilla.
developer.
wiki.
.sourceforge.net</PRE
></TD
></TR
></TABLE
></P
><P
> The actual <TT
CLASS="FILENAME"
>default.action</TT
> is of course much more
 comprehensive, but we hope this example made clear how it works.</P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN4462"
>8.7.3. user.action</A
></H3
><P
> So far we are painting with a broad brush by setting general policies,
 which would be a reasonable starting point for many people. Now, 
 you might want to be more specific and have customized rules that
 are more suitable to your personal habits and preferences. These would
 be for narrowly defined situations like your ISP or your bank, and should
 be placed in <TT
CLASS="FILENAME"
>user.action</TT
>, which is parsed after all other 
 actions files and hence has the last word, over-riding any previously
 defined actions. <TT
CLASS="FILENAME"
>user.action</TT
> is also a 
 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>safe</I
></SPAN
> place for your personal settings, since
 <TT
CLASS="FILENAME"
>default.action</TT
> is actively maintained by the
 <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> developers and you'll probably want
 to install updated versions from time to time.</P
><P
> So let's look at a few examples of things that one might typically do in
 <TT
CLASS="FILENAME"
>user.action</TT
>: </P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># My user.action file. &#60;fred@example.com&#62;</PRE
></TD
></TR
></TABLE
></P
><P
> As <A
HREF="actions-file.html#ALIASES"
>aliases</A
> are local to the actions
 file that they are defined in, you can't use the ones from
 <TT
CLASS="FILENAME"
>default.action</TT
>, unless you repeat them here:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Aliases are local to the file they are defined in.
# (Re-)define aliases for this file:
#
{{alias}}
# 
# These aliases just save typing later, and the alias names should 
# be self explanatory.
#
+crunch-all-cookies = +crunch-incoming-cookies +crunch-outgoing-cookies
-crunch-all-cookies = -crunch-incoming-cookies -crunch-outgoing-cookies
 allow-all-cookies  = -crunch-all-cookies -session-cookies-only
 allow-popups       = -filter{all-popups}
+block-as-image     = +block{Blocked as image.} +handle-as-image
-block-as-image     = -block

# These aliases define combinations of actions that are useful for
# certain types of sites:
#
fragile     = -block -crunch-all-cookies -filter -fast-redirects -hide-referrer
shop        = -crunch-all-cookies allow-popups

# Allow ads for selected useful free sites:
#
allow-ads   = -block -filter{banners-by-size} -filter{banners-by-link}

# Alias for specific file types that are text, but might have conflicting
# MIME types. We want the browser to force these to be text documents.
handle-as-text = -<A
HREF="actions-file.html#FILTER"
>filter</A
> +-<A
HREF="actions-file.html#CONTENT-TYPE-OVERWRITE"
>content-type-overwrite{text/plain}</A
> +-<A
HREF="actions-file.html#FORCE-TEXT-MODE"
>force-text-mode</A
> -<A
HREF="actions-file.html#HIDE-CONTENT-DISPOSITION"
>hide-content-disposition</A
></PRE
></TD
></TR
></TABLE
>&#13;</P
><P
> Say you have accounts on some sites that you visit regularly, and
 you don't want to have to log in manually each time. So you'd like
 to allow persistent cookies for these sites. The
 <TT
CLASS="LITERAL"
>allow-all-cookies</TT
> alias defined above does exactly
 that, i.e. it disables crunching of cookies in any direction, and the 
 processing of cookies to make them only temporary.</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ allow-all-cookies }
 sourceforge.net
 .yahoo.com
 .msdn.microsoft.com
 .redhat.com</PRE
></TD
></TR
></TABLE
></P
><P
> Your bank is allergic to some filter, but you don't know which, so you disable them all:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ -<A
HREF="actions-file.html#FILTER"
>filter</A
> }
 .your-home-banking-site.com</PRE
></TD
></TR
></TABLE
></P
><P
> Some file types you may not want to filter for various reasons:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
># Technical documentation is likely to contain strings that might
# erroneously get altered by the JavaScript-oriented filters:
#
.tldp.org
/(.*/)?selfhtml/

# And this stupid host sends streaming video with a wrong MIME type,
# so that Privoxy thinks it is getting HTML and starts filtering:
#
stupid-server.example.com/</PRE
></TD
></TR
></TABLE
></P
><P
> Example of a simple <A
HREF="actions-file.html#BLOCK"
>block</A
> action. Say you've
 seen an ad on your favourite page on example.com that you want to get rid of.
 You have right-clicked the image, selected <SPAN
CLASS="QUOTE"
>"copy image location"</SPAN
>
 and pasted the URL below while removing the leading http://, into a 
 <TT
CLASS="LITERAL"
>{ +block{} }</TT
> section. Note that <TT
CLASS="LITERAL"
>{ +handle-as-image
 }</TT
> need not be specified, since all URLs ending in
 <TT
CLASS="LITERAL"
>.gif</TT
> will be tagged as images by the general rules as set
 in default.action anyway:</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ +<A
HREF="actions-file.html#BLOCK"
>block</A
>{Nasty ads.} }
 www.example.com/nasty-ads/sponsor\.gif
 another.example.net/more/junk/here/</PRE
></TD
></TR
></TABLE
></P
><P
> The URLs of dynamically generated banners, especially from large banner
 farms, often don't use the well-known image file name extensions, which
 makes it impossible for <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
> to guess
 the file type just by looking at the URL. 
 You can use the <TT
CLASS="LITERAL"
>+block-as-image</TT
> alias defined above for
 these cases.
 Note that objects which match this rule but then turn out NOT to be an
 image are typically rendered as a <SPAN
CLASS="QUOTE"
>"broken image"</SPAN
> icon by the
 browser. Use cautiously.</P
><P
> <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ +block-as-image }
 .doubleclick.net
 .fastclick.net
 /Realmedia/ads/
 ar.atwola.com/</PRE
></TD
></TR
></TABLE
></P
><P
> Now you noticed that the default configuration breaks Forbes Magazine,
 but you were too lazy to find out which action is the culprit, and you
 were again too lazy to give <A
HREF="contact.html"
>feedback</A
>, so
 you just used the <TT
CLASS="LITERAL"
>fragile</TT
> alias on the site, and
 -- <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>whoa!</I
></SPAN
> -- it worked. The <TT
CLASS="LITERAL"
>fragile</TT
>
 aliases disables those actions that are most likely to break a site. Also,
 good for testing purposes to see if it is <SPAN
CLASS="APPLICATION"
>Privoxy</SPAN
>
 that is causing the problem or not. We later find other regular sites 
 that misbehave, and add those to our personalized list of troublemakers:</P
><P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ fragile }
 .forbes.com
 webmail.example.com
 .mybank.com</PRE
></TD
></TR
></TABLE
></P
><P
> You like the <SPAN
CLASS="QUOTE"
>"fun"</SPAN
> text replacements in <TT
CLASS="FILENAME"
>default.filter</TT
>,
 but it is disabled in the distributed actions file.
 So you'd like to turn it on in your private,
 update-safe config, once and for all:</P
><P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ +<A
HREF="actions-file.html#FILTER-FUN"
>filter{fun}</A
> }
 / # For ALL sites!</PRE
></TD
></TR
></TABLE
></P
><P
> Note that the above is not really a good idea: There are exceptions
 to the filters in <TT
CLASS="FILENAME"
>default.action</TT
> for things that
 really shouldn't be filtered, like code on CVS-&#62;Web interfaces. Since
 <TT
CLASS="FILENAME"
>user.action</TT
> has the last word, these exceptions
 won't be valid for the <SPAN
CLASS="QUOTE"
>"fun"</SPAN
> filtering specified here.</P
><P
> You might also worry about how your favourite free websites are
 funded, and find that they rely on displaying banner advertisements
 to survive. So you might want to specifically allow banners for those
 sites that you feel provide value to you:</P
><P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ allow-ads }
 .sourceforge.net
 .slashdot.org
 .osdn.net</PRE
></TD
></TR
></TABLE
>   </P
><P
> Note that <TT
CLASS="LITERAL"
>allow-ads</TT
> has been aliased to 
 <TT
CLASS="LITERAL"
>-<A
HREF="actions-file.html#BLOCK"
>block</A
></TT
>, 
 <TT
CLASS="LITERAL"
>-<A
HREF="actions-file.html#FILTER-BANNERS-BY-SIZE"
>filter{banners-by-size}</A
></TT
>, and 
 <TT
CLASS="LITERAL"
>-<A
HREF="actions-file.html#FILTER-BANNERS-BY-LINK"
>filter{banners-by-link}</A
></TT
> above.</P
><P
> Invoke another alias here to force an over-ride of the MIME type <TT
CLASS="LITERAL"
> application/x-sh</TT
> which typically would open a download type 
 dialog. In my case, I want to look at the shell script, and then I can save
 it should I choose to.</P
><P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ handle-as-text }
 /.*\.sh$</PRE
></TD
></TR
></TABLE
>   </P
><P
> <TT
CLASS="FILENAME"
>user.action</TT
> is generally the best place to define
 exceptions and additions to the default policies of
 <TT
CLASS="FILENAME"
>default.action</TT
>. Some actions are safe to have their
 default policies set here though. So let's set a default policy to have a
 <SPAN
CLASS="QUOTE"
>"blank"</SPAN
> image as opposed to the checkerboard pattern for
 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>ALL</I
></SPAN
> sites. <SPAN
CLASS="QUOTE"
>"/"</SPAN
> of course matches all URL
 paths and patterns:</P
><P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>{ +<A
HREF="actions-file.html#SET-IMAGE-BLOCKER"
>set-image-blocker{blank}</A
> }
/ # ALL sites</PRE
></TD
></TR
></TABLE
></P
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